CRF230F Shop Notebook

18 September 2018 | Web Link | Doc Link | POC

“I want to thank you for creating this amazing Shop Notebook on the CRF230F. Being new to the whole sport/trail riding with my recent purchase of a 2017 CRF230F this notebook has been an amazing guide to make it the ultimate ride for me. ... Just thought I would send an email thanking you for this amazing dedication that's put into this and I'm sure something like this isn't done overnight.” -- reader comment

Reading Tip: The web layout is dense. Narrow your browser window to make it easier to read.

This crowdsourced notebook documents CRF230F mods and maintenance in detail with links, photos, and step-by-step sequences.

Since it is a Google Doc you are welcome to comment, edit, or add content. To do this you will need a Google Account or Gmail account.

You can search for any topic with Control-F (hold down Ctrl and F at the same time). You can be notified of updates. If you want to print it out, the Doc format is better. As of December 2017, the length is over 200 pages.

Please note there are no advertisements or affiliate links. This might change in the future.

WARNING: The reader acknowledges that: -The information here is crowdsourced and may be incomplete or inaccurate. -The information is not reviewed or approved by the manufacturer, importer, or dealers. -Mechanical work is inherently hazardous, and can result in property damage, injury, or even death. -Carrying out maintenance or modification actions on a motorcycle may void the warranty, remove or violate regulatory compliance, and/or create unsafe conditions. 


[*] = new material, Summer 2018



Video index


Philosophy of the CRF230F: “Miles of smiles”

“1/2 the cc's, 10x the fun”

[*] Buying a used CRF230F

Alternatives to the CRF230F?

[*] Reducing weight

[*] Fork upgrade options

Triplett fork mods

[*] Shock options

[*] XR400R fork swap

What is the range of sag recommendations?

Suspension tuning

Suspension 2.0: Triplett fork mod and Podium settings and results

Suspension 3.0: CRF150RB Forks

Step by Step CRF150RB Fork Swap

Initial impressions

Spring rate 2018


Handlebar positioning

Foot peg repositioning

The Xplodee build: August 2017

[*] Absorbing vibration

Clutch lever upgrade

Seat issues and upgrade options

Seat Concepts upgrade and results

A low mirror under the handlebars

Uncorking the CRF230F: Current state of the art

Float level measurement and adjustment

Changing the carburetor needle on a 2008 and later model

Carb tuning techniques

Jetting adventures 2016

Jetting adventures 2017

Ignition timing mod by changing flywheel key

ProCom CDI and Dial-A-Jet upgrade

The IntelaJet

Water crossings

Exhaust upgrade options


The PowerBomb header

EO Outlaw system

Sound level measurements

[*] Is it possible to quiet the CRF230F while maintaining power?

Engine mods


Clutch upgrade options to handle more power

Carb upgrades

OKO 28mm PWK Carb Upgrade

OKO 28mm PWK on an uncorked bike

Tuning the PWK for the CRF230F


Frickin’ Jim Build

Mixxer BunnZilla Build

JXG Build

[*] BTR Build

[*] Mike H. 272 Build

[*] Cop Build by BTR

Rocky Mountain bling build

Electrical modifications

Street conversion

LED headlight upgrade with stock stator

Adding a neutral indicator LED

Upgrading the start/stop switch

In praise of horns on trail bikes

Electrical upgrades 2018

New control panel with voltage meter

The quest for automatic lighting

Stator upgrade

What about brake mods?

[*] Tires

What about trials tires for dry trail riding?


Carrying extra fuel

Chainsaw rigs




Air filter

Spoke tightening



Rear suspension inspect and grease

2017 linkage service

Steering stem how-to

Cam chain tensioner: Replace with Tokyo Mods?


Fork Seals

What about Seal Savers?

Chain guide

Reinstalling the tank and seat

Fuel and Storage

How to be notified of updates to this document


ThumperTalk is the definitive forum for the CRF230F

Special note on “BTR” (bajatrailrider). BTR is frequently cited because he owns and maintains a fleet of CRF230Fs and other bikes in a tough environment. He rides a heavily-modified CRF230F thousands of miles each year and has been doing this for a very long time. And he tries every visitor’s bike. This experience level provides a unique perspective on what works and what lasts. You can search for “BTR” with Control-F and see his build here.

Ramz has the original dedicated site dating back over a decade

Frickin’ Jim CRF230F Mods is an encyclopedic list of all known mods

CyclePedia CRF230F Service Manual Kindle $25

Parts schematics



Video index

Frickin’ Jim Channel

See Frickin’ Jim build below




2003-2007 230F's have 2.2 US gal tank w/ 0.4 reserve

2008+ 230F has 1.9 US gal w/ 0.4 res

“They made tank smaller so they can put a skinnier seat on it, so it feels more flickable...” post


Philosophy of the CRF230F: “Miles of smiles”

“The test of the machine is the satisfaction it gives you. There isn't any other test. If the machine produces tranquility it's right. If it disturbs you it's wrong until either the machine or your mind is changed.” Robert M. Pirsig, Zen and the Art of Motorcycle Maintenance: An Inquiry Into Values

Videos. When modified, the CRF230F is known as a formidable singletrack machines. Here are some examples of riding CRFs

CRF230F evolution page (translated from Japanese)

“I have a Trials bike (Montesa 250cc 2T), a CRF250X (set up for PNW trails), and a modified XR200R (full Powroll 218, disc brakes, lightened, USD forks, etc), and each has performance that suits some types of terrain and riding styles better than others.

All three have Trials Competition tires so traction is equalized leaving weight, suspension, chassis geometry, and power delivery.

If I ride typical open trails the X is my choice, but it sucks on tight technical single track and is not a good riding experience.

For tight technical single track my choice is the Trials bike but it is tiring for trail riding of any distance and doesn't have the suspension for high speeds.

The XR218 is the best of both worlds; a shorter wheelbase than the X, weight between the X and Trials bike, good suspension, and tractable power delivery. So, even with the differences between a 230 and a XR200, a properly set up and lightened 230 could do the same." (post)

“For slow short tight technical work the small chassis is a benefit.  For fast long open work the small chassis is a detriment.  Since 80% of our riding is slow short tight technical work it works for us.  No bike will do everything right.  It's all a compromise. When we ride we almost never stand up.  We ride mostly sitting and/or hovering just over the seat.  If we stand up it is just to stretch out a bit.  The way we ride you must stay tucked in and keep your CG low and centered.  If I needed a more open cockpit I would likely be riding differently and likely have a bigger bike like an XR250.

My CRF230 makes more torque right off idle than the old 265 did in the low-mid area; it is just like a little diesel.  It cares not what gear you are in and is so forgiving it is a bit silly.  It reminds me of a miniature XR600 in terms of the engine's  forgiving nature.  If I miss a gear change and come to a tough section with too little engine speed I simply hit the gas and it chugs away. - VortecCPI post

“XR200...  CRF230...  These two engines are brothers from the same mother...  Mike Coe told me Honda came to him during CRF230 engine development and asked him what he had learned over all his years of working with the XR200 engine.  He said Honda listened and incorporated a lot of his ideas into the new engine.”  - VortecCPI post

“So with a temporary lapse of reason I went and bought a KTM 450.. and then both boys decided they needed to be all extreme and now the air cooled stuff wasn't good enough.. KTM went to oldest boy... Got the younger an rm125 since he was now following travis pastrana on Instagram... And I got a yz450 for me... And what a nightmare relapse into insanity that has been!! Weekly rebuilds on the RM... Taking out loans to afford KTM oem parts.. not to mention the added KTM pleasure of needing to break a timing chain every time you want to do rings or a piston... And me learning that yz450s need manhole covers as flywheel weight to stop the cough and abrupt stall in tight woods... Sanity returning to xr level now... The boys now have PLENTY of tool time under their belts and can fix whatever they want to ride... I am beyond sick of all the hassle again... Same reason I went xr before the boys felt like riding... I will keep the YZ so I can puff out my chest and show people my nasty steed if I feel the need...haha... But I am once again looking for more fun and less hassle...” - Mixxer post

“The CRF230, like the XR200, is a bike that just seems to deliver very easy and pleasurable riding.  Not too big, not too small, not a lot of power but enough to get you there. Miles of Smiles.” - VortecCPI post

“1/2 the cc's, 10x the fun”

I’m a new 230F owner who is sharing my first ride impressions and what I think about this bike. My guess is, there are plenty of people who are in my shoes, wondering if a 230F is right for them. Warning: this could get a little long.

First off, I got back into riding about 6 years ago after a 30-year break. I rode and raced in my teens. I’m 6’5” and about 260 lbs, so I’d naturally lean towards a larger bike. Over the last 6 years, I’ve bought an XR600R, an XR400R, an XR200R and XR100R (for my boys), and finally, a WR450F a couple of years ago.

I kept the 400 (which is a restoration project), the 200 (for my youngest son) and the 450 for me. I thought the 450 would be the be all, end all for my needs - single and dual track trails up here in northern Idaho.

The 450, while a nice bike, isn’t all that great for the riding around here. It’s better on faster, more wide open spaces. It’s tall and carries its weight high, and the engine doesn’t lug like a big XR does - I loved both the 400 and 600 for their tractor-like pull. I didn’t love kickstarting the 400 or 600. I want the magic button.

So I spent the past year trying to figure out what my next bike was going to be. I ruled out the KTM’s, Beta’s, Husky’s and other high-priced bikes. I actually preferred an air cooled bike after working on my XR’s. I thought strongly about an AJP PR4 (we have a dealer in Spokane), though I had concerns about parts and the Zongshen engine long-term. The AJP lust did shift my thinking towards a small displacement bike.

I turned my attention toward the CRF230F and the TTR 230. I started reading the forums and blogs, and the CRF had an edge with the aftermarket stuff to make it better and faster. And, my own XR experiences were pleasant.

I watched Craigslist for a while - lots of modded bikes that were at the ceiling or a little beyond what I wanted to spend. I figured I’d be looking at a mid-2000’s model to fit my price range, which means a 10+ year old bike could be a gamble. Fortunately, for every ratted-out looking 230, there was one that was a girlfriend’s/daughter’s/older-adult-bike that was hardly ridden and stock. I found one of those - a 2004, bone stock, and pretty clean. So I bought it a few days ago.

I mounted up a Shinko Trail tire on the back and a new knobby on the front, went to Canfield Mountain and spent a couple of hours getting lost on the network of trails. Canfield, the locals know, has some rocky trails, some mudded and deeply rutted trails, some thick brush and tree cover, logs, and a few trails I would never think about going up or down on my 450.

I was really amazed how this stock, 13 year-old 230 could haul me around! Throttle response was great for a carbureted 223cc engine - I spent most of my time in 1st and 2nd gear, and even in 3rd and 4th, roll-on was tractor-like. It never seemed to bog or hesitate; it pulled without complaint. I stalled it once due to my hesitation early on in the ride, going up a very tight, rutted section. Later on, as I got familiar with it, I trusted it to get up or down wherever I was going.

It is nimble. It feels a little small for me, but not pit-bike small. I will probably find someday that a rear-disc brake might be better in some situations - I rode through some water and didn’t notice any fade. The riding was too slow to really test out the suspension - it worked just fine. I would probably put $$$ into suspension over the engine, if I had to choose between the two. The motor is amazing considering it’s a small, air-cooled 2-valve, carbureted 6-speed. Like I say, ½ the cc’s and 10x the fun of the big bikes.

Am I glad I bought it? Yes - I wish I would have bought one 6 years ago! Would I buy another one? Hell yes! Would I recommend this bike to others (especially people over 6’ tall and over 250 lbs)? Absolutely. I’d recommend it to people who live in wooded, single-track areas (maybe not desert areas if you want to ride fast). I’ve read many comments about the 230 keeping up with the KTM’s and other wood warrior bikes in the gnarly single-track area - I believe it now. It would embarrass the 450-and-up machines.” - post

“I very much identify with the comments about switching over to the 230 from a full on race bike. It took me a long time to swallow my pride and finally embrace the 230. I couldn’t get past the idea of having brand new, top of the line, super fancy KTM’s, Beta’s, Yamaha’s, etc but I wasn’t any faster or safer on these versus my little 230.  I can ride the 230 for longer, faster, more control and safer, and go just about anywhere. I wish I had made this transition a long time ago.” - post


[*] Buying a used CRF230F

The CRF230F has been around for a long time with minimal changes and is a very tough bike so many people buy them used.

Don’t buy a beater because it is possible to find barely ridden bikes for good prices.

BTR says: “What I learned is take your time you find the deal -- buy a beater it will be a loser. All the CRF230F’s I bought for me and friends took months to find. As new, 2003/2004, $1200 to 1500. Poor Mike was tired looking for few months so he got a 2006 for $2000. A beater, but he did not care. As he said, well I will build this bike anyway. He is a expert on bike builds. After he built it he had to take it apart many times to change the beater parts that were not seen at time of rebuild.” post

What you are looking for was purchased for family use, the novelty wears off, kids grow up, and they are offered up. Here is an example of a seller who knows the whole short history of the bike. This is the kind of guy you want to meet.

If there is no title, you generally don’t even want to look at the bike. So ask up front if the seller does not say. And make sure it is in the hand of the seller -- not the finance company on newer bikes. (If the title has simply been lost, a replacement is available at any motor vehicle office.)

Note the title will say “Off-Highway Vehicle.” Be aware that street conversion has gotten more and more restrictive in most states.

AZ and CO are exceptions. SD is the classic source of mail-order license plates but be aware that in 2017 policy changed. It is now difficult or impossible to get a true “street plate” for a CRF230F. They are happy to sell you an OHV plate... which is not valid in any other state.

Being a dirt bike without an hour meter or odometer, you don’t have any real data to go on. But if it looks flawless outside then it is probably good inside too.

Of course some bikes have not been maintained so you have to exercise due diligence.

If the bike is rougher, more investigation is needed and it helps to have a seller who knows the history of the bike and is forthcoming. The engine is very tough so if it has gotten oil changes and air cleaner cleanings then it is probably good. A good place to start is checking the air filter.

Don’t be afraid to walk away from a beater. There will be more. These bikes are not in short supply. is a good site to check because it aggregates CL, eBay, and other sources. Get in the habit of checking it daily and you will see leads pop up. Don’t get discouraged if there is not much available. It varies a lot. Save your money and be patient. AZ and SoCal almost always have these bikes listed.

Here is a price graph from BikeFinds showing the bikes it is currently listing. At this time the prices are up, probably because it is riding season.

Above: JXG on 17 and 16 August 2018, with thanks to BTR


Alternatives to the CRF230F?

What about a modified XR200R? Classic forerunner of the CRF230F but suspension upgrades are needed and see post on overstressing the transmission. And no electric start, which can be a show-stopper for the older rider.

What about an XR200R with an eStart CRF230F engine? It’s real good. Post

What about an XR250R? The late-90’s air-cooled XR250Rs are fantastic bikes: powerful, comfortable, low weight and sophisticated suspension not found on the stock CRF230F. See Frickin’ Jims review here. The big problem for many riders? No electric start as Jim laments here.

But... a footnote... BTR notes that a ‘96-04 XR250R "Baja" model was sold in Japan with e-start. Major project to convert a US bike, but it could be done if the parts could be obtained somehow. (His friend Mike H. has converted an XR400 to e-start using parts from a 400 quad. Also a big project including crankshaft.)

What about a CRF250X? Piston replacement at low hours (50 to 100?) is a drawback of riding this race bike which is optimized for power not longevity on the trails. “Rode a bunch of tight ST yesterday on my XR218 for the first time in a month and it was a stark contrast to my CRF250X on the same trails. The XR218 has similar weight and steering rake to a CRF230F and I was much less tired on the XR, and it was fun rather than work.” post

What about the AJP PR4? Sluggish and quality problems; see review here

What about the GPX Moto FSE 250R? “The LXR is kind of the missing link in Chinese bikes. It’s about half way there.  The real stand out for me was the nc250 motor. It has run so good without problem that it has changed my mind on what China is able to bring to market these days.  On top of that motor parts are very easy to get and are very affordable.

I decided to pop for the fse250r because of the whole package it offers.  Smooth counterbalanced motor that will run all day without complaint. 6 speed transmission that is good off road, but can still get down the highway. Good 3 phase alternator that can power lights and GPS etc.  Keyed ignition for security. Electric start is a must/kicker back up.  This GPX checks all the boxes for me.  It will get a good thrashing this year and we will see how it goes.” - chadzu post

Small rider? Look at the Beta 125 RR-S. Have not seen much discussion of this bike (here is one review) but the price point and weight are both low. Could require suspension upgrades for more technical riding.

What about a 2011 Gas Gas EC250? “I was very particular in looking for a replacement for my 230, and this bike is by far the closest I could find that's a true upgrade without any real downside.  I wanted all the big positives of the 230 (low seat, e-start, low-end grunt, good handling for tight trails, reliability), but an upgrade in the suspension, ergos, and power department (which is where the 230 is severely lacking).” Post and see earlier posts in thread.

Aggressive and skilled rider? The Beta XTrainer is a great bike but the stock forks can be unstable and dangerous even at low speeds (post). Upgrading the forks is needed for serious technical riding (at least for riders over perhaps 190 lbs) and is quite expensive. And if you don’t have the reflexes the 37 HP and low weight will put the hurt to you real quick. Not for beginners, see here.

Husky FE250? 50 state legal and so off-highway capable that Husky does not bother with a pure dirt four stroke as pointed out in a recent Dirt Bike mag (received in July 2018). One problem! Seat height is real high.

Above by JXG and others, 14 August 2018


[*] Reducing weight



CR80/85 fork swap (approx weight)



Shorai battery






Shift / brake pedals






Rear sprocket hardware






Suspension linkage



Modified stock front brake rotor *



Rear brake



Aluminum snail adjusters



Upper engine mounts



Rear hub aluminum axle spacers



Front rotor by EBC *



XR200 coil









* = duplicated component

There are basically three zones in the chart above:

Zone 1. 30 to 50 oz. The fork swap is a big weight savings, but cost me $900. On the other hand I did not do it to save weight. The battery is not cheap, and I have a lead acid spare which I keep on float / desulfation at least every couple weeks. So I’m not in a hurry to buy a lithium battery.

Zone 2. 10 to 20 ounces. If you are looking to replace worn-out components there may be some payoff in here.

Zone 3. Up to 10 ounces. Can add up. Payoff depends on your goals and what your time is worth and your enjoyment factor of modding.

Bottom line: If you are going to need a new battery anyway, lithium may be the bang for buck opportunity.

Getting to 240 lbs post

Chuck post and post

Tire Weights (2009) post

Spreadsheet link


Thread is here

Above: 15 August 2018 v3 by JXG


[*] Fork upgrade options

September 2018: This section has been rewritten to emphasize that USD (upside-down) cartridge forks are for MX not trail riding and that the best technology for trail riding appears to be the XR400 fork swap: a RSU (right-side up) cartridge. -- JXG

FIRST UP: If you are not happy with your forks, the first thing to check is sag. If your sag is wrong, your spring rate is wrong. If your spring rate is wrong, the forks are not going to perform even with inverted, nano-tech, cryo-cooled cartridges that incorporate alien technology. The main thing is the spring. Both static and dynamic sag are critical--they must be in harmony or the spring rate is wrong. See What is the range of sag recommendations? for specs.

Quick Test: Hit the brakes. Does your front end dive a lot? If yes, your spring rate may be off. Measure your sag.

Acronyms and terms

DR = damper rod (older tech)

USD = up-side down: fork tubes are at the bottom (newer tech)

RSU = right side up: fork tubes are clamped at the top (older tech)

Mini bike = not a full-size bike. The CRF230F is a mini bike.

Next question: What kind of riding do you want to optimize for? It matters. Here is why:

“Then along came cartridge forks. Next were up-side down [USD] versions designed to control compression speeds to absorb MX jump landing, just the opposite of the compression speeds needed to absorb sharp edge bumps during trail riding.”

“The modern MX chassis is much more rigid than a steel trail bike chassis and that is important for a smooth ride [at race speeds]. USD forks are also more rigid than normal forks. Mix the two and you have a very harsh trail ride. The mini bike USD forks are not as rigid as full size USDs and work better for trail riding. I have a CRF250X with a twin spar aluminum frame and 47mm Showa USD forks; a very rigid chassis that has a planted feel and is easy to ride fast but stock is brutally harsh on my local trails.” Chuck post

By upgrading the forks, you could turn your trail bike into a race bike.

Upgrades correspond to three eras of technology:

⧫ Damper rod (DR) uses orifices to modulate oil flow for slow plush riding on trails with sharp edges like rocks and roots (60’s technology)

⧫ Cartridge uses shim stacks to modulate oil flow for fast riding on smooth MX tracks (80’s technology)

⧫ USD (upside-down) or inverted forks are more rigid and lighter (reference). Note all USD options are cartridge, but not all cartridge are USD.

Price zones for upgrades

Zone 1: Improve the stock forks

Theme: Big improvements without a lot of work or cost. Most will perceive significant improvements that change their riding experience. Beyond this zone improvements will get expensive and you have to ask: Will I even notice any difference in the riding I do?

1.0 Tune the stock damper rod fork

1.05 BTR budget air spring option: “I just did two more stock 230s with air caps at 2.5 psi. 100% improvement over stock fork. Why only because stock is so bad, but cheap fix.” “ I have done 4 bikes already all owners like it, even me. Of course people will say no air is the best - they’re right. Not when you’re talking stock 230 fork. Remember that this fork is so bad it does not take much to make it better.” - BTR post

Making your own air caps page

1.1 Damper rod cartridge emulator

1.2 Triplett damper rod mods

💙💙1.2 Triplett is a known sweet spot in price/performance: “Works excellent for 75% of owners (IMO) for faster than average trail riding but certainly not for any serious MX racing... Certainly AT LEAST 50% of all 230F owners would feel perfectly happy with these mods.” post  “The forks are wonderful over rocks, no deflection, very smooth. ... Bottom line, this was an awesome price-performance modification.” 💙💙

Zone 2: Easy swap to a better damping rod fork

2.1 86-95 XR250R Fork Swap is a slight upgrade from another Honda

PAUSE HERE. Before you go any further... Could a stock damper rod (DR) fork with mods be plush enough for trail riding?

Zone 3: Easy swap to a RSU cartridge Honda fork

Theme: Bring over RSU cartridge that CRF230F never got

3.1 96-04 XR250R swap

Other perspectives on the XR250R swaps, but excluding Terrain Tamer: 

In my opinion a set of stock late-model XR250 forks are a waste of time and money.  Once you get them sprung properly you have forks with way too little rebound damping. Even with factory springs rebound damping is inadequate. A set of CRF150R or CR85 forks makes good sense as they are superior to the late-model XR250 forks. If you spend some time speaking with Bruce Triplett you will find though XR250 forks seem a lot better they are not.” - VortecCPI post

BTR: “CRF250/450 fork too rigid and not good idea on 230... Even on my 450s I junked them in favor of XR650R forks.” post

3.2 Terrain Tamer special build using 96-04 XR250R core

“It works over a much more varied terrain than any other fork or revalved fork available to off road riders.  It is more supple than a stock KDX/XR fork but has more bottoming resistance than a revalved MX fork set up for off road.” - Bruce’s Suspension 

Terrain Tamer forks are forks that have been gutted and have highly-customized internals.  They are like nothing else on the market and are not even remotely close to late-model XR250 forks except for what they look like on the outside. Terrain Tamer forks will cost you about $600 so they are reserved for expert riders with expert wallets.” - VortecCPI post, more details by VortecCPI

This will make the forks into simply the BEST off-road / trail / woods / desert / dual-sport fork you can have. Forget about fancy USD forks, they won’t come close.” - Frickin’ Jim

3.3 XR400 fork swap <= Ultimate for trail riding?

BTR: “The 230 I built for friend with XR400R forks are working better than all my USD forks in the whole fleet” post

See Cop Build for details

Zone 4: Serious swap to an USD cartridge Honda fork

Theme: Bring over the newer Honda technology... but remember it is aimed at racing not trail riding. Many Zone 4 photos and details are available on the Ramz forks page. A very extensive review of parts is on the fork details page.

Worth it? “I have a CRF150R front end with RT Gold valves on my XR218 and they are good, a big improvement over the stock damper rod forks like the 230’s use, and much lighter than stock or the big Showas.” - Chuck post

Is there any preference between CR80/85 and CRF150R/RB forks?

“Most agree that the CRF150R forks are the easier and ‘better’ option because they have more modern valving and a bigger axle.” - xplodee post

“CRF150R & RB [full-size wheels] forks are my primary interest because they were developed for a heavier motorcycle and will thus be more suitable for the relatively heavy CRF230F, and they are still being developed for current year models.” - Ramz

Do I have to revalve / change shims? For CRF150R/RB forks, a noted modder states that he has never made any changes to the cartridge internals for moderate trail riding: only appropriate springs and fork oil.

The theory of why this works? Motocross forks are not a good idea for trail bikes. They are designed for high fork velocity and are way too stiff for slow plush riding. So why do the CRF150RB (the "B" means full-size wheels) forks work on the CRF230F? The CRF150RB is designed for teenagers to ride very fast and hard. It has a very stiff suspension with lots of damping... for a 150 lb rider. If you put a 200+ lb rider on the forks, with proper springs, the damping is likely to be about right. This relatively simple "open-cartridge" fork provides the sophistication of a modern design while being easy to work on.

What about clickers? “Those clickers [CRF150R] are just bypass bleeds and only good for fine tuning. On my XR200 I needed to run with them both all the way out but the bike would then wallow like an old car with bad shocks so I needed softer valving and less clicker.” post

4.2 Emig CR/CRF125/250/450 Inverted Fork Swap


4.3 Emig CR80R/CR85R/CRF150R Inverted Fork Swap


Zone 5: Difficult swap to non-Honda technology

Theme: Bring over more exotic technology like YZ250 forks

But do you really need the most complex forks on a trail / enduro bike?

Summary: There seem to be three sweet spots in these zones:

Triplett modified damping rods:

CRF150R forks by xplodee:

What you can tune

Damping rod forks

1.0, 1.2, 2.1

1.1 Gold Valves

Cartridge forks may have:


11 April 2018 latest by JXG

12 September 2018: Rewritten to de-emphasize USD cartridge forks for trail riding

Link to this section:


What about a fork brace?

“The fork brace, IMO, made the bike handle much better because of less deflection over slippery tree roots, rocks and especially ruts. The front end actually started to go in the direction that I wanted to go instead of flaying around. I will not ride my 230 with conventional forks without a fork brace ever again. It just works so well.” - Adnohguy post

“The 230 forks flex quite a bit. They deflect more than 2 inches. Getting out of ruts or tracking straight in really rough stuff can be difficult. The fork brace is a great mod for the bike. Every review I ever read agreed that is made a big difference in stability in the rough stuff.” - post

“You'll benefit from a fork brace if: - post

1. you ride in the sand. It helps prevent head shake.

2. you try to ride out of a rut.

3. have trouble holding a line at speed.

4. you're a big guy. It'll just feel more precise.

Review of SRC in 2006 (no longer available): “The only downside is that since so much fork flex has been eliminated, the forks feel stiffer and harsher when encountering trail trash, even though the fork action hasn't changed. You definitely feel more feedback from any and all front wheel impacts with trail trash, both in your hands and your wrists. Overall, it makes the bike just a bit more tiring to ride.

The upside is the greatly improved steering precision. I really didn't notice how much the front wheel was wandering after being deflected by impacts with minor (2" and less) trail trash until I felt how much more solid and precise it is with the fork brace in place! It not only allows you to go faster, but faster with improved confidence! Perhaps the biggest surprise, however, was the improved feel and front tire traction feedback during hard cornering, even when the surface was smooth and flat! To me, this was every bit as beneficial as the improved steering on rough ground. I regret that the feedback is more harsh now, but the benefits were well worth it!” - CRF’s Only review from 2006. Modern fork upgrades may reduce the downsides noted above.

$109 RSW fork brace

Above: 11 December 2016, 7 January 2017 by JXG


Triplett fork mods

Over the past couple of years the Triplett damper rod mods have become popular because they are cheaper than Gold Valves and many believe they work better. Bruce drills a pattern of proprietary (unpublished) holes in the damper rods. The theory is explained here under “Orifice Size and Location”

Here are some favorite quotes on the Triplett mods:

“Works excellent for 75% of owners (IMO) for faster than average trail riding but certainly not for any serious MX racing:

“My gut tells me that this would be more than great for at least 75% of 230f owners. Certainly AT LEAST 50% of all 230f owners would feel perfectly happy with these mods.

“... Previously I had stock forks, so Bruce's updates are way way better.  The stiffer spring holds the bike up more, and the damper rod mods seem very well matched to the springs.  Compression and rebound seem about spot on.  There were a few areas where I thought the rebound could have been a bit slower, Bruce recommends a change to a heavier oil for that, but I am going to hold off and ride the bike a bit more.  I had a couple of high speed (fork movement) hits that jolted me a bit more than expected, but my other main bike is a KTM 300 with closed chamber forks valved to perfection, so pretty unfair to expect that performance from the CRF230F fork.  The forks are wonderful over rocks, no deflection, very smooth.  I did some light moto on it, but I think I'll wait for the Fox shock before getting too crazy. Bottom line, this was an awesome price-performance modification.”

The 2nd generation Triplett damper rods transformed my bike into a COMPLETELY different ride than the whole 5 years with the emulators.

Did not seem to make a difference on how rough or off camber, all tree roots, square edges or Loose rocks, the forks actually out performed my Works Performance rear shock for the very first time. ... I was able to push my bike harder while using all available power much more often than ever before.

I had more confidence with out bottoming or deflecting off of obstacles, the wheels tracked where I needed to go. ESPECIALLY on steep down hills. No more bottoming! Same fork springs as before. Much more confident on loose off cambers. Also Happy to report: No more almost jerking my hands from the bars, no more sore wrists, elbows and shoulders.


In 2014 I thought Gold Valves were a significant improvement over stock. In 2016 I decided it was time to upgrade again.

Removing the damper rods

You can either buy new damper rods or use the stock ones. What you cannot do is reuse DRs that have already been drilled out for Gold Valves. Bruce cannot braze up these large holes.

So I bought a new set of DRs to send Bruce, but still had to get my old ones out.

Here is the process by VortecCPI, with my comments in bullets:

1. Loosen DR bolts: you will probably need to use an impact wrench.

1.5 Loosen upper fork pinch bolts

2. Loosen fork tube caps

3. Support bike with front tire off ground

4. Remove fork tube caps

5. Remove fork springs

6. Lower front and collapse forks

7. Place catch containers under DR bolts

8. Remove DR bolts - Drain oil - Do not pump!!!

9. Fasten a magnet to a wood or PVC rod

10. Use rod and magnet to remove DRs

If the DR cups move it will just be off center. I have never ran across a set of forks that had enough room for them to turn sideways. If they move just take a small screwdriver and reach up through the bolt hole and into the bottom of the DR cup and recenter it. Then slide the fork slider all the way to the top (bottomed). This will trap the cup and keep it centered” - Motoman354 post. JXG: I have done this twice with no problem.

Installing the Triplett mods

What you need:

Make sure his drilled holes did not leave any burrs on the inside of the rods that may decide to come loose and cause major internal problems with them floating around in the fork oil. - Adnohguy post

When the mods come back, you get get an instruction sheet. Here are my notes and clarifications on Bruce’s numbered items:



Drop springs in with the cut end first, then the PVC spacers, then install the caps and torque to ___

Bruce has a particular approach to fork installation. The longer and more clear version is on his website. The critical step is rotating the axle. But on the CRF the axle does not rotate: it screws in and stops.

[*] Shock options

Summary: Stock shock is “horrifying” as Frickin’ Jim puts it, but can be modified to a level not as good as the Hagon. Hagon is not ideal for technical riding due to its simple emulsion damping system but is popular, available, and a big step up from stock. 1986-up XR250R shock is best performance but takes time and money to find and get rebuilt. CR85R has also been used. Fox Podium is very good but discontinued. There are a couple of other options that are more rare.

^^^ Stock shock, Hagon, and Fox Podium RC2

What about revalving the stock shock?

“I have been running a Hlebo revalved shock for over 5 years on my 150f. Way better than stock, but I Guarantee it's no Works, Hagon, or Fox shock. It's right on the verge of being acceptable. My Triplett damper rods make that same shock unacceptable.” - Adnohguy post 

“We had a Hlebo shock for quite a few years. ... When I bought my buddy a Hagon he really didn't think it would be that much better.  He was pleasantly surprised and pleasantly wrong. Way more comfort, way more traction, way more braking, way more acceleration.  Way more... Hlebo very good...  Hagon way better...” - VortecCPI post

Stock shock internal mods: brief note here

Hagon shock

Hagon M63051 purchased by JXG from Bruce Triplett in 2014. Replaced with Fox Podium in 2016. A few notes...

Stock spring rider weight claimed by Hagon: 75-100 Kg (165 to 220 lbs)

This is an very wide range: “The nominal out of the box spring rate is for riders from 165 - 220 LBS, which I personally do not believe to be accurate.. One spring does not fit riders (with proper sag) ranging from 165 to 220 LBS.”

Typically the sheet that comes from Bruce Triplett states that a Hagon stock spring is 9 KG = 503 lbs/inch 

But Brandon at HyGear called Hagon in the UK on 9/8/16 and they gave him a spring rate 56 lbs less:

Why is the Hagon stock spring even softer than the Honda stock spring at 502 lbs/inch (post)? Unknown. But keep in the mind the CRF230F is intended for lighter riders.

Falcon 1 analysis. “At the time I purchased the Hagon shock from Bruce Triplett my body weight was 215 LBS, and I was clearly too heavy for the Hagon factory spring to achieve the proper sag. I had to adjust the Hagon shock eight (8) turns to get the proper 3 inches of race sag. Hagon's Spring Adjustment instructions advises not to exceed six (6) complete turns, so obviously the Hagon shock spring is not intended for 215 - 220 LB riders.

That said, I currently weigh 155 - 160 LBS (lost 60 LBS) since I purchased the shock, it works flawless for my current body weight. post

I could not acquire the correct static/race sag until I was around 180-185 LBS.” post

Bottom line: To achieve correct static and ride sag, heavier riders may need a heavier spring.

Hyperco spring options for the Hagon: 475, 500, 525, 550 lbs/inch. $110 plus shipping from HyGear post

(Note there are at least two posts stating the stock springs work perfectly for 200 lb riders. But no sag numbers are provided.)

1986-up XR250R shock

BTR has stated this is the best shock he has ever ridden on a CRF230F.

Pro-Link Kayaba single shock with spring preload, 20-position compression and 20-position rebound damping adjustability; 10.6 inches travel

Stock spring rate of XR250R shock?

1986 to 1987: 9.1 = 508 lbs/inch BTR post

1988 to 1995: 9.3 = 519 lbs/inch BTR post

1996 to 2004: 600 lb spring BTR post post

Year????       : 9.9kg = 554 lbs/in post

Cannon Racecraft has springs for 1996-2004: 11 to 12.6

RaceTech has springs for 2004 and up

Factory Connection does not seem to have any XR springs

Eibach appears to have springs for 1986 to 1995: 644 and 672 lbs/inch (Brook Suspension, UK)

If you are going to need a heavier spring, try to get a 1996 or later shock as springs are more available.

“Mine has been revalved to be slightly stiffer. Raises bike up, works perfect for light or heavy riders. ... For the 1986 up XR250R / XL250 shock it is a 5 minute mod to put a small notch in in the frame (Top) bracket.” - BTR post

Also may need to bend the "cup" back and install spacers on the right side.

The reservoir hose needs to be set around 9:30 o’clock to pass out to where it can be mounted to the frame. Here are the hose angles that BTR uses:

Note that when the shock is rebuilt the reservoir cap should be left off. This way if the hose needs to be turned slightly and leaks, the shock can be pumped up with a high-pressure bicycle pump. A little air won’t hurt since air is mostly nitrogen. Ask the rebuilder what the pressure should be before doing this.

^^^ 2005 CRF250R shock does not have a remote reservoir and thus requires mods to the airbox area. Other specs: “Std. wgt. 5.3 kg/mm spring. Spring o.d. is 3.56". Bolt, center to center, shock length is right at 19.5". Top bearing width is .788" (20mm) and bottom clevis width is .795" (also 20mm). Both ends use a 10mm bolt diameter.” - Doogee57 post and photo above

CR85R shock by RickyRacer

CR85R shock has a 14mm shaft, piggy back reservoir, compression and rebound adjustment and has aftermarket pistons available post

Spring: Used a 1989 XR600R shock spring with ID grinding: 10 KG = 550 lbs/in

Length: 15.25 inches yields 11 inches travel with stock CRF230F linkage post, post

Shims: “already feels much better than the xr600r shock I was using!!!!” post

^^^ CR85R photo courtesy of RickyRacer

1989 XR600R shock

“I'm using a 1989 XR600R shock and have been playing with two stage valving on it. I love it. It's getting much closer now.” post [link seems to be wrong]

Race Tech G3-S custom series shock post is $1,099 or without a remote reservoir for $799 post 

^^ Race Tech G3-S custom series photo courtesy of Chad Walsh

YSS post and post

WORX is reportedly still in business post, Facebook page. “Have used a Worx remote reservoir rear shock for years on my 230 and it works at least as well as my Hagon does.” - Adnohguy post 

Ohlins is expensive post

^^^ WORX and stock shock. Photo courtesy of Ness le French

^^^ WORX and Ohlins shocks. Photo courtesy of Ness le French

Fox Podium Shock

JUNE 2017 The Podium is no longer available: BTR post

Installation slide show with lots of pix

See below for sag recommendations, the settings JXG used, and results...

Shock weights

JXG updates on 22 March 2018, updated and reorganized on 11 September 2018



[*] XR400R fork swap

(9/10/2018 version, still a work in progress)

Right side up (RSU) forks for ultimate plushness? BTR post, Doogee57 post on unsprung weight, Chuck post

BTR first discussion (15 May 2017), w/details on XR650R triples post

BTR more info (30 May 2017) post

Forks to use. 1997 to 2004 XR400 forks per jeffrow68 post

Triple clamp. XR650R per jeffrow68 post and also BTR


Shims. “If your XR400 forks are after 97, they have 12 shims. Remove 8 so you have 4 left.” BTR post.

Oil. “3 wt rear shock oil 4 inches from top” BTR post

Springs cut. “The top coil: grind it flat to size after heating. Be sure to check length before you do it. Because after heating cut top coil you drop it just like factory. Please note when you grind it flat you lose a little more spring height.” BTR post

PVC spacer. “On Cop bike spacer was 1-1/4 inch even with forks pulled up 1 inch in clamps.” BTR post

Brake line. 2001 CR125R. RR post

Caliper. CRF230F. RR post 

Wheel. 1989 XR600R with correct bearings for 17mm axle. RR post

RickyRacer other config post

Fork test by BTR. “The four of us rode the Cop bike. ... Nitpicker said it only took 5 feet to tell the XR400 fork was more plush. We then tested jumping / rocks / ruts / g-outs / whoops that suck on a 230.

“Tight uphill trail with rocks. High speed sand wash and tight trail with lock to lock turns. Did we leave anything out? The damn XR400 fork wins hands down. Mike tried everything he could do to make them fail.

“Here is the difference: the XR400 forks are shorter by 1-1/4 pulled up about 1 inch in triple. They have 1.5 more rake then CR85/150 fork are 1/2 in longer. I'm still 100% happy with my CR85B forks but I will do the plug the hole trick. I will also mount the XR400 forks for long test but as it stands the CR85/150R fork is the loser. I was impressed with the Cops bike: it was capable of going faster over the whoops than I had nerve.” BTR post

Other stuff...

“XR400 forked 230 after long test”: this is a long complex post that discusses why the CR85 and CRF150R forks are not as plush on sharp edges. Focus on the midvalve.

^^^ Photo courtesy of RickyRacer

Above by JXG on 10 September 2018



What is the range of sag recommendations?

Bruce explains the duct tape method. RaceTech has a slightly more complex method that averages two measurements.

Stock forks

Front travel* = 9.2 inches = 233 mm

Rear travel = 8.9 inches = 226 mm

* caveat about rated travel and actual travel post

CRF per VortecCPI 5/27/12 (link): “I too thought my bike came back with too much race sag but they explained a woods bike needs more sag to accommodate the ever-changing trail conditions. More sag allows the wheels the ability to better follow the terrain.”

Front: 22%-25% race sag (CRF230F = 2.02"-2.38")

10/18/15 (link): “If Free Sag is between 5% and 10% of total travel spring rate is within range. For the CRF230F this means Free Sag [static sag] should be between 0.45" and 0.90".

Rear: 30%-33% race sag (CRF230F = 2.70"-3.00")

10/18/15 (link): “If Free Sag [static sag] is between 5% and 10% of total travel spring rate is within range. For the CRF230F this means Free Sag should be between 0.45" and 0.90".  If Free Sag is less than 0.45" the spring rate is too low.  If Free Sag is more than 0.90" the spring rate is too high.”

CRF per Chuck (link):

“However some, including Dwight Rudder, suggest rear rider sag as high as 33-34%: 2.9 to 3.0 inches

“There are two ways of measuring rider sag which may explain the different recommendations: 1. With the rider seated, and 2. With the rider standing. The latter places less rider weight on the rear suspension resulting in lower sag values than seated.”

Why measure sag while standing? “The reason for standing is simple - it is consistent. Seats on dirt bikes are very long. If the rider sits on the seat in different locations it will throw the measurement off.” RT And if you stand a lot while riding.

Why measure sag while sitting? If you don’t stand much?

CRF rear race sag should be 3.25 (36%) per Bruce Triplett, 9/6/16

CRF rear race sag should be 3 (34%) per Bruce Triplett, 2018 instruction sheet


Suspension tuning

Suspension tuning by Bruce Triplett: Reformatted web version for easier reading (Google Doc version). Section on Adjusting in the field.

Suspension 2.0: Triplett fork mod and Podium settings and results

Rider weight = 225 lbs with full armor and backpack

Spring rate converter 

Front suspension version 2.x

Dialing it in. This chart shows how far off my front sag was and how it ended up at the right place:

The labels are cut off above. Here they are:

Rear suspension version 2.1

Initial settings for shock breakin (version 2.1):

Rear version 2.1 based on BagLock1: "I run my Fox Podium X with as little damping as possible.  About 4 clicks of low-speed compression and 1 or 2 clicks of high-speed compression.  Rebound has as few clicks as possible for the given terrain.  Fox also told me to run it ‘loose’ with as little damping as possible.”

BTR: “After riding testing the Fox shock over two years now. We run the 550 spring  We are between 160/165 pounds [without gear].  Compression from full soft to 1 or two turns out. Hi speed Adjuster full soft then out 1/4 turn. I need check rebound then I will post. Note when you turn rebound adjuster harder it also makes Comp stiffer. We run sag no rider 1in or 5/8in.” post 

BTR comment on break-in: “I found it took a very long time for break in [the Podium RC2]. I don’t go by hours that’s for unreliable bikes. So it took about 8 rides at over 100 miles a day. It just kept getting better every time I rode it. My Comp slow/Hi speed set very soft love it.” “I forgot to add. When you adjust the rebound more hard you will find out you then need one click less on comp.”

See Frickin’ Jim Episode 11 for his settings


Riding impressions

My first hint that the bike had changed was a test ride around the block. No more fork dive when braking. You don't realize how bad this is until it is gone.


Started up the slightly rocky trail and noticed that the front end was staying heads up and going where I pointed it. Like the absence of brake dive, you just can't appreciate this until you feel it.


Wait, why can't I feel the rear end of the bike? At this point I realized I must have left the rear wheel in my garage. The Fox Podium was somehow levitating the rear of the bike along. Like somebody was carrying it while I tested out the forks. No sensation of rocky trail trash. It was spooky. I was beginning to think this was going to be quite a test ride.


Getting into the rougher terrain, the front end continued to just go where pointed even in steep loose stones. I had been riding these exact trail sections all summer and the difference was amazing.


With proper static and race sag, the front wheel now rolls over obstacles instead of sliding out or bouncing off. It seems counterintuitive but the physics is this: Appropriate stiffness equals plushness.


Meanwhile, what about the Fox? It was like sitting on a pillow. Going from the Hagon stock spring at 447 lbs/in to the Fox at 598 lb/in made the difference. With dual-speed compression (DSC), the Fox is like a two-band radio. One compression damping circuit handles the high frequency inputs while the other handles the low frequency inputs.


Fast bumps and slow bumps, the Fox just sucks up the energy and turns it into fluid movement and heat. Phenomenal. I have ridden a KTM 350EXC-F and Beta Xtrainer on these same trails and my CRF230F is now the plushest of all. (But I would guess the other bikes could be further tuned for my weight and riding.)


If you ride in rocks, the stock shock is just frightening. It is like a roulette wheel or random number generator, pitching you sideways. Point and pray is what I remember about it. A noted CRF tuner told me the first time he rode his CRF230F he thought it had been sabotaged.


The Hagon is a big improvement at $430. But it is a simple shock with gas and oil mixed together in an emulsion. There is a single damping adjustment for both compression and rebound. In rocks or heavy terrain where there is high and low frequency shock movement, there is simply no comparison with the Fox and its three adjustments.


If you don't ride in these conditions, then you will be quite happy with the Hagon. If you have not compared the Podium and Hagon on the same rough trails, you may be quite happy with the Hagon.


Pretty soon I noticed I was riding along stones on the edge of the singletrack, just to feel the absence of sensation and visualize the fluid movement in the shock. Entertaining. And the reduction of fatigue over the miles was noticeable.


Approaching a familiar rock garden, I noticed that I tensed up preparing for a thrashing. But the Fox just floated through. Yes, there were still bumps. It's not magic. But I would estimate there is 25 to 50% less energy going into my joints and spine with the current setup.


Much of the credit goes to the Podium and its reservoir. But again, I've learned the hard way you have to have the correct spring rate to produce the correct static and rider sag--the spring is the primary thing. First order control. If the first order control is wrong, nothing else will compensate.


The front end is not quite at the same performance level. After all, it is a damping rod fork even with Triplett mods. On sharp edges, it is harsh because it does not have the high and low frequency circuits to deal with both low and high velocity movements. But still a big improvement from stock springs and Gold Valves.


Steep loose ledgy downhills were another revelation. Instead of sliding out, the front end stayed under control. One particular series of ledges has always resulted in bucking and more than one wipeout on the last step. With the proper ratio of static and race sag, the front spring accomodated the bumps without packing down. Whole different experience.


The other big Podium difference is in jumping. I like to do a lot of slow 6 inch to 18 inch jumps--probably not a good idea for health and safety but I love it. The Hagon has been hard on my back, even wearing a lumbar belt. The Fox with its high velocity circuit is like landing on a beanbag chair. The visceral pleasure of these landings was the capstone of an amazing ride. (Again, velocity here means movement of the shock not the bike.)


What I've learned:


-Sag is a pain to work with, but it is critical. I had been riding half a bike because I would not bite the bullet and get my static and race sag in order with spring upgrades and sag adjustments.


-For riding in rocks and rough terrain, upgrading to a multi-circuit (high and low velocity movement) shock is a complete game changer even at modest speeds. If you ride hard, you don't have to ride fast to see improvements that you will feel and enjoy.


-If you jump, your body needs a high velocity damping circuit to absorb that energy before it goes into your spine


-There is a lot of focus on suspension upgrades for racing. What about for aging? Few race, all age. If you are putting lots of hours into rough riding, all that energy is going somewhere. The body damage is significant. (I can't ride a hardtail mountain bike on trails any more--I need 5 inches of Fox air shock under my spine.)


At this point, $700 for a shock seems worthwhile to me. It has transformed my riding experience in a way that I would not have believed possible. The reduction of fatigue is worth the price alone. And the reduction of body impact will help keep me riding for many years to come.


One final note: It is interesting that Beta offers the Fox RC3 as an upgrade on $9000+ machines. I would guess that Fox is at the top of the game with the DSC. Thanks to Fox and BTR for making the Podium available for the CRF230F. http://www.thumperta...ox-shock/page-1

Posted at

Ride photos are here: There are small captions at the bottom.

Afterthoughts, March 2017: With more comparisons riding cartridge forks (AJP PR4 and Beta Xtrainer) I now am less enthusiastic about my current CRF setup. Yes, it is improved but in rocky conditions the forks especially are just not plush.

More experiments


Results. Tried Forks 2.2 = no spacer above BBR. Mostly the same trails again. On sharp edges it was a bit more compliant and less harsh. But it seemed like maybe I gave up a little bit of precise tracking in loose turns. I'm not sure. Need to do some back to back comparisons, since it is easy to remove and install the spacer. post


Suspension 3.0: CRF150RB Forks

This large project followed the definitive Ramz guide. See Fork upgrade options for the rationale for this “Zone 3” upgrade.


Which forks to use? Ramz Tip: When you buy, try to find out the exact model and year of the forks. There are slight differences in spring rates and oil levels between the R and RB, and 2007-11 and after 2011. See table in Service Manual, p. 1-9.

Worksheet based on Ramz Part List, organized from top to bottom
➤ = decision to make


➤ Need to purchase 9/8-inch bars? The bar clamps will be 19 mm or 0.75 inches higher than CRF230F stock.

If you have a 1-inch to 9/8-inch converter / riser, than you will need a 9/8-inch to 9/8-inch riser.

Triple clamp

➤ Bearings? Given the cost of this project, may be worthwhile replacing while you have things apart. See Steering stem how-to

91015-425-832 x 2
Partzilla $19, RMAM $25
53214-KA3-732 Top dust seal
Partzilla $4
53214-MCJ-751 Bottom dust seal
Partzilla $3

Grease: “Use the specified grease (urea based multi-purpose grease with extreme pressure agent) for the tapered roller bearings and dust seals: - Excelite EP2 (
Kyodo Yushi) or equivalent - Stamina EP2 (Shell) [S&A] or equivalent”

➤ Steering stop

  • Ramz $35*. Note this is a high-precision machined part that fits exactly.

➤ Stem options: The CRF230F stem is too short and welded in place, so another stem must be used post

  • Option A: Machine CRF150R stem to fit CRF230F steering head
  • Press stem out
  • Machine bottom triple clamp so that stem is countersunk 6-8 mm (post)
  • Turn down stem to fit bottom bearing
  • Press stem back in
  • Option B: XR250 stem replacement
  • Press CRF150R stem out
  • Press XR250 stem in 53200-KT1-770


➤ Seals? 51490-GBF-J21 x 2 Partzilla $15, RMAM $16

(Again, if the forks are used consider replacing. If not, they will surely begin leaking soon.)

➤ Fork springs

                IIN: 0.26 to 0.40 PDF

                CrfsOnly $114

     32448: 0.22-.50 even rates PDF Dimensions

➤ Suspension fluid: 1 qt

  • Ramz tried 5W and now uses 10W
  • Amsoil #10 $14/qt
  • Bel-Ray HVI 10W Partzilla $15/qt RMAM $13/qt

➤ Air bleeders? See What about air bleeders below.

➤ Gold Valves??? post


➤ Fender assembly
Partzilla $41, RMAM $43
Bolt (6x16) x4 93404-06016-08
Partzilla $1

Fork protectors

➤ Fork protectors

Right 51610-GBF-680ZB or 51610-KSE-A50
Left 51620-GBF-680ZB or 51620-KSE-A50
Bolt x6 90113-MAC-780


➤ Brake hose 45125-KRN-A31. You may not need this hose. My stock hose fits even with a chainsaw rack.

  • New Partzilla $60, RMAM does not stock
  • Galfer FK003D412F
  • eBay search: not a common item

➤ Caliper bracket Kit CRF230F04 - Ramz $125*


➤ Axle
Axle 44301-KSE-000
Partzilla $17
Nut (14mm) 90305-197-013
Washer (15mm) 90510-KY1-000

(Caliper bracket kit includes spacers: “The axle spacers are used to mount the stock CRF230F front wheel to the stock CRF150R forks using the stock CRF150R axle.”)

*These kits are manufactured by a small startup company in Colorado. Ramz handles distribution as a service to the CRF community, but all proceeds go to the manufacturer.

What about air bleeders?

In a cartridge fork, air pressure or vacuum builds up: see How-To. You can bleed the forks with a screwdriver with the front wheel off the ground:

There are a couple of options for tool-less button bleeders:

There are two problems with these buttons: they seem to have serious quality problems, and fitting them into the very limited space of the fork cap is difficult--see the photo above.

Finding forks to swap

Here is the 2008 CRF150RB front end I purchased off eBay:

CRF150R has more modern and conventional shim stack in the midvalve post

10.8 inches travel, per link

Parts diagram for this fork

What is the issue with stem length? [added 10 December 2017]

The CRF150R stem is too short to fit through the frame of the CRF230F with enough threads left over. But it is close and might appear to work. Below is with no allowance for bottom bearing. The bottom bearing is out so the triple is flat against the frame:

But as soon as you add a slight allowance for the bottom bearing... there are no threads at the top. Note top bearing is in place in this photo:

CRF230F is on the right, you can see how much longer the stem is:

The CRF150R stem can be pressed upward or a longer stem substituted. More on that below.

What is the change in handlebar height? 

Top of triple clamp to midline of handlebar clamp:

What is the effect of fork oil level?

From Owners Manual, p. 101


Step by Step CRF150RB Fork Swap

Part 1: Replacing the fork seals and installing springs

Tools and workspace

I followed the process in Ramz and the service manual.

1.1 Disassembly. After loosening the adjuster screw and fork cap (17 mm), the damper rod must be separated (15 mm):


1.2 Fork seal replacement. With the forks disassembled, I replaced the fork seals because one was leaking slightly. In the photo below, the dust seal has been pried up and the retaining clip is visible inside the fork tube. Under this is the oil seal itself. See p. 12-18 for details.

The left slider bushing had a slight ridge of Teflon material. I sanded this down with fine sandpaper.

Installing the new oil seals was very difficult even using the Tusk driver: see Fork Seals. It may help to start the seal very evenly all around.

Note: I did not disassemble the fork damper to count shims, etc. But at a minimum check the compression adjusters to make sure they click smoothly.

1.3 Spring fitting. The Cannon Racecraft springs are a little too small to fit on the plastic spring guide. A tiny bit of material can be easily removed. There should be no resistance between the guide and spring. I used a coarse file then sandpaper to make sure there were no shavings left:


Note: The original CRF150RB springs each have one scribe mark so this means standard 0.36 springs were in the forks (p. 97)

1.4 Oil filling. This can get messy so a vise really pays off. Below I am using a large syringe to measure the fork fluid.

Note: When the Belray arrived I realized it said nothing about forks. But I found the following at link: “AMSOIL STM #10 Replaces The Following Lubricants: Belray HVI 10W”

While less precise, I prefer to use the a fork oil level tool:

Note: Be sure to wash the rubber plunger in dish detergent and it will last longer. If you leave oil on it, the rubber will quickly deteriorate. Even with washing it can start to get sticky. I coat it with silicone O-ring grease between uses.

IMPORTANT UPDATE: It is critical to get all the air out by following the Ramz process exactly. Ramz adds by email: “I usually let the forks sit overnight after filling with fluid and pumping air.  I adjust fluid height the next day.  Even if I'm in a rush, I wait 30 minutes or so between filling/pumping and then checking.”

1.5 Reassembly. Getting the damping rods up through the springs is a bit tricky. I tried the Ramz method but decided I prefer to use a wire.

Here is the setup. First, notice the wire at right is holding the fork tube up so I can get to the top of the damping rod.

Loosen the lock nut slightly so that the wire can be wrapped around the damper rod. Run about 2 feet of stiff through the spring. Secure the end to a stopper like a wrench so it won’t pull through.

Now wrap the wire tightly under the screw. The wire and wrap need to be strong enough to resist several pounds of force:

Insert the spring into the fork and carefully pull the damper rod up with the wire. Once it gets to the top, carefully squeeze the spring down just enough that you can get the fork cap on. At this point the spring will not fall back down:

Remove the wire, tighten the lock nut down against the spring guide (not too much), and tighten the fork cap on using two wrenches as explained by Ramz.


2.0 The triple clamps

This section is a little intense because of the bearing race installs. Study the manual.

2.0 Remove the old forks and triples. But first, make a couple measurements so you know the geometry. In my case,

Top of axle collar to base of steering head / top of bottom triple = 647

Top of axle collar to top of steering head = 820 mm

2.1 Machine shop work. I decided to do Option A: machine the CRF150RB lower triple and stem. A rider / machinist did this part for me. He pressed out the stem, then turned it down so the newly-exposed part would fit the bearing. With the stem in the lathe, he made a discovery. The stem is not straight. He did not measure it, but estimates 0.005 off. This was not good, as it implied the front end has taken a huge hit. Are the forks bent?

I asked him to proceed. Next he milled the 1/4-inch step in the bottom triple. Finally he pressed the stem back in. No heating or cooling was used in these pressing operations. Here is what it looked like:

2.2 Bearing races replacement. I used the budget method in Steering stem how-to. Driving in the top race using the old race as a driver:

2.3 Bearing install. Page 12-28 shows lower bearing installation with a press and special tool. This is not necessary. I installed the lower dust seal, then heated the bearing on an electric stove and it dropped on.

Not quite. I heated the bearing, dropped it on... and realized the dust seal had been forgotten. Fortunately, I was able to heat the bearing with a heat gun and by tapping the stem on the workbench the bearing came off again. Whew. Unfortunately the second time I heated the bearing, I left it on the stove for awhile and the rollers turned blue. Not good. If this was a high speed bearing I would have replaced it. But I decided to proceed.

Here is what we are putting together, from page 12-29 of the manual:

I did not get the ideal grease equivalent, but instead used Jet-Lube 202, a moly-lithium grease that I have used on swingarms. The assembly sequence is shown on page 12-30. And now, the moment of truth...

The stem now reaches through with plenty of threads.

3. Wrapping up

_Snug the top nut

_Install those big golden boingers, making sure all the cables go where they should. Insure that nothing will get pinched by the steering stop.

_Tighten the top nut

_Install the forks

_Install the brake adapter. Be sure to use the round head bolts. The other ones will stick out just enough to hit the brake rotor bolts.

_Install the wheel and axle using the spacers in the kit. Tighten the axle nut and make sure there is no interference with the brake caliper.

_Ignition switch: Here is how I mounted it

I found that my tire was within a few millimeters of the lift deck, just like with the original forks. So I did not need to use the measurements made earlier.

Now let’s back up a bit. With this new axle we can now do the Bruce Triplett alignment process on his website.

First, remove the wheel again and loosely install the axle.

Here is the process, reformatted. It only takes a few minutes to do and confirms the fork alignment.

This next step is VERY IMPORTANT.  This is the PROPER WAY to install forks.  ATTENTION – if improperly installed, the forks can’t work to their full potential.  First install the left fork (left is determined as if you were sitting on the bike) into the triple clamps.   (A little WD 40 sprayed on the fork tubes will make them slide in easier.)  The measurement you took before you removed the forks will allow you to re-install the left fork at the proper height.  

VERY IMPORTANT – Torque the pinch bolts to factory specs [22 NM].  Next, install the right fork in the triple clamp at approximately the same height as the left fork and LIGHTLY tighten ONLY ONE of the pinch bolts.  

This next step is CRITICAL –install the axle into the forks, grab the axle between the left and right fork, and begin rotating the axle.  As you rotate the axle, loosen the pinch bolt on the right fork and move the right fork up and down until you locate the place where the axle turns most freely.   Now, at this position, torque the pinch bolts to factory specs.  

Install the wheel and brakes, and tighten the axle and/or axle nut.  

The following does not apply to the CRF15R forks because it does not have axle pinch bolts:

Torque the axle pinch bolts on the LEFT FORK ONLY.  Now, you need to work the forks up and down.  The best way is to tie the cycle down in/on your trailer, or ride the cycle SLOWLY up and down the driveway, and pump the front brake level several times, making the forks move deep into the travel.  Now you can TORQUE the RIGHT axle pinch bolts.

_Install SealSavers... highly recommended.

_Install the fork guards

_Now, the brake hose. Attach it to the fork guard clamp. If you just use the number plate, it is possible the original hose will be long enough. I run a headlight cowling or a chainsaw rack depending on the season, so I may be installing the longer hose.

_Set the compression damping at the base of each fork. There are about 20 clicks on mine. Go full hard, then 7 clicks to soft for the standard setting (page 100)

_Set the rebound damping. Turn all the way to hard, then back out 1-1/4 turns for the standard setting

_Adjust the handlebars

_I made some modifications to the front wiring bundles and key switch; see chainsaw rack.

_Go back over every fastener, making sure everything is tight


Many thanks to Ramz for his extensive research, development, and documentation of CRF fork swaps.


Unfinished business?

The fluid mystery

I followed the Ramz process exactly and Honda recommendations on fluid volume but it didn’t work as expected:

28 July: By email, Ramz provides the only explanation possible: I did not get all the air out. See step 1.4 above for more on how to make sure all the air is removed.


Initial impressions

I weigh 178 lbs. Ride weight is 225 lbs in full armor with hydration pack. Chainsaw takes it up to around 242 lbs.

This was a big project but I was prepared to be disappointed. I thought there could be a 20% improvement that was only apparent over a few rides.

The first test was going off the curb at my house then hitting it straight on at around 10 mph. The results were encouraging. The curb hit was very plush.

Next I went to a rocky area. When riding straight at 8 to 10 inch ledges the fork just absorbs the hit. There is a slight thunk and you are up the ledge.

Doing "monster truck" rolls off of ledges to about 14 inches sometimes (not always) resulted in the sound of something hitting. Not hard, but at full compression there is slight interference.

Inspecting the new fender, there is a small skid mark at the center. And it looks like the GOP3177 (a huge soft tire) width is causing it to brush the sides of the fender. You can see this on the right side of the photo:

But the impact is very plush with no hard bottoming. I don’t consider this slight interference anything to worry about.

Moving on to chunky trails, the forks did well in complex rock gardens with lots of quick impacts:

The forks are much stiffer than stock--but not too stiff--so the bike tends to go where it is pointed.

The 3/4-inch risers that came with the forks put the bars at a good height. I can stand up pretty comfortably. Any higher would be into “Easy Rider” territory.

For really slow trails where the bike is doing a “rocking horse” up and down and over rocks, there was not much difference:

At these very slow speeds, it seems like the oil is moving so slowly through the fork that it doesn’t much matter what valving is present. But even here I think the cumulative reduction in impact over a few hours reduces fatigue.

The 0.42 spring rate seemed to work well both with and without the chainsaw. When descending steep ledgy downhills with the saw on, there is still some bucking. I will try some increased rebound damping for this configuration. (Update on this below: the sag was way off.)

The stock brake hose was long enough with the saw rack; you can see it in the photos above.

Bottom line: Two thumbs up!


More impressions: July 2017

Fire restrictions were lifted and I got to test on familiar chunky trails where I have ridden all of my bikes and a few other’s bikes. The chainsaw was off for this ride. Without same-day, back to back rides, it is always difficult to compare exactly.

With that said, the ride was a bit of a letdown. I felt like the forks handled sharp-edged hits the same as the Triplett “GEN II” mods. For some hits it felt a bit plusher and I think over a day of riding it does make a difference in reduced fatigue. But not a large difference like the step up to Triplett mods. It is possible that tuning will further refine the forks. (28 July: Also, I have discovered that the forks have too much air and not enough fluid in them. See fork fluid mystery above.) Here is how I rate the differences now:  

Bottom line: While a fun and interesting project, I currently do not believe the CRF150RB fork swap was cost effective at $900 (!). I reserve the right to change my mind in the future. Post

Project budget

Above: 28 July 2017 by JXG (started 16 June), updated slightly on 10 December 2017


Spring rate 2018

Here is what RaceTech says for CRF150RB with a 225 lb rider (210 plus they add 15 lbs in the calculator):

Some data points:

And my sag measurements were: Spreadsheet, click on “Forks150” tab at top

See What is the range of sag recommendations here: generally 22 to 25%*

You can see my sag with the Cannon 0.42 springs was 3.2 and it should be more like 2.3.

Update, April 2018. I realized I was using the stock fork travel. For CRF150RB with 10.8 inches travel, the above are 29% and 21% sag (of rated not measured fork travel*)

* When calculating percentages, see this caveat about rated travel and measured travel post

Cannon kindly did a swap for 0.50 springs with these results:

Below you can see where I was with Triplett mods and BBR springs, how the 0.42 springs first installed in the CRF150RB forks were too soft, and how the 0.50 springs are much closer to the target:


Above: 10 April and 24 January 2018 by JXG

Link to this section:



No tuning data on the CRF150R/B at



Handlebar positioning

the Rox 2-inch risers, I initially had them rotated so far forward that the bars were located past the fork tubes. That caused some very quick/weird handling in turns and resulted in a lot of headshake when being ridden on the road. I rotated the bars back a bit so they are almost over the fork tubes and the result is much more like stock handling while raising the bars a bit more than I'd like, but it is very usable and much improved as far as opening up the cockpit. Keeps you a bit forward which really helps in keeping weight forward on the bike as well as improving the bar/peg/seat relationship. Feels like a "regular" bike now.” - kkim post

Rox 2 inch and Power Riser 3 inch (I think):

Images from Frickin’ Jim video show how far forward his Rox are:

Rox makes a 3.5 inch

Power Riser makes 2 and 3 inch tall

JXG: I have a 2 inch Power Riser and 77 mm height Carmichael bars, so this is about a 1.5 inch increase over stock without changing cables. Mine are above the fork tubes and will go no further forward.


Foot peg repositioning

Frickin’ Jim explains the problem:

The peg-to-handlebar relationship on the CRF230F is actually a bit strange. The stock geometry is not ideal for controlling the bike while standing on top of it. Many people believe, after riding the 230, that this is because the handlebars are just too low. That is not entirely true!

The main problem is that the handlebars and pegs are too close together horizontally, leaving the rider with very little leverage to control the bike. Look at the picture above comparing the peg-to-bar angle of the CRF250R and the CRF230F. This shows the problem. On the CRF230F, the peg-to-bar slope is much more vertical than on a standard full-size dirt bike. This is not good.”

TT thread

12/2/13 brent j:

I tried the bike with the footpegs moved back 35mm today. I rode it with the bars forward and std peg position, bars forward and pegs back then pegs back/bars std.

I won't go into details but pegs back and bars forward seems to me to be the best combination.

In tight going (single track) I have room to get up forward and really steer it.

Now climbing rocky hills I have room to move around and steer where I want to go and I can keep the front light when I want to.

There's more room to move around and shifting my weight now has a bigger effect on how the bike handles.

I gained a big advantage in moving the bars forward and about the same improvement by moving the pegs back.

After trying all the available combinations my view is to make to make changes in the following priority

Move the bars forward about 35mm AND the pegs back about 35mm

If you can only do one then I'd move the pegs back first and the bars forward second

I think that if you move the pegs any more than about 35mm you will run into problems with the shifter becoming too short. Any more than about 35mm and you may need to go to a linkage. The shorter the lever the more effort required to shift and the harder it is to find neutral.

I wouldn't drop the pegs any lower then std as today I had the pegs dragging in a rut and my feet were pulled off the pegs.” - brent j post

12/2/12 thumperjay

I installed the RSW clamps with 2.5" rise... and rode for the first time today. I was able to stand and ride almost all day, it was a brilliant upgrade. Running Renthal bars and the risers in the middle position, which are inline with the forks.

Quickened up the steering, took a bit of getting used to... but after an hour, it was obvious it was the right upgrade... rather than just some zeta risers on the stock triples, with the bars behind the forks.

Much more roomy and comfortable for standing long periods of time.

Fugaldo design: 30 mm back post

30x26 design is 10 mm lower, which could cause dangerous dragging as noted by brent j above post

CRF450R conversion: 2010 pegs used by Fugaldo post

10/20/15 MetricMuscle: “I recently procured some CRF450R footpegs.  I have found when the bracket is mounted to a flat vertical surface, the footpeg itself isn't flat or parallel to the ground, the end sticks up, even when rotated.  Has this been mentioned and adjusted for?  I have read thru this thread but not every post.  I could easily mod the peg itself to sit flatter.


The Xplodee build: August 2017

There is now a solution: the xplodee build, with details and additional mods by Ramz...

“Would I buy these brackets again? Well actually, I plan to install a set on my second CRF230F. The whole upgrade at around $200 may seem expensive to some riders, but it's worth the money to me to get some foot comfort for those long all-day rides.” - Ramz

I purchased a set with used brackets and new pins/springs/cotter for $125 total, and a set of used pegs for $24. Stay tuned for more. -- JXG

Ramz: "flat hex-head bolt (M10x1.25-50 grade 10.9) that I found at TrueValue"

Above 7 October 2017 by JXG


[*] Absorbing vibration


Clutch lever upgrade

A recent thread on clutches got me interested in lighter clutch pull to reduce riding fatigue and tendon wear. I rigged up a luggage scale to do an approximate measurement and got these numbers:

On the CRF, you can see that lubing the cable and switching to the MSR Pro Raptor Adjustable made a big difference: 15% then another 40% for a total of 65% reduction. Pretty good. But switching to the MSR required some changes to the bar layout. Here are the details.

Note: This is an easy upgrade limited to the hand lever. For a more in-depth upgrade you can modify the other end of the system at the clutch: internal option and extending the lever option.

Clutch lever upgrades

You can spend some serious money on a clutch lever and perch, for example:

$115 Righteous Stunt Metal

$126 Pro-Taper Profile Pro RMAM

$160 Works Connection

I decided to go with the “MSR Pro Raptor Adjustable Clutch Lever Assembly Hot Start Shorty Red” because of its reasonable price and details about how it reduces pull.

The closest MSR page is here. Here is a more detailed description that I pieced together from a couple of sources:

Below, you can see the three holes corresponding to the top, middle, and bottom position. The hot start lever at the bottom has already been removed:

Below, you can see the cable angle adjuster. There are three notches that it can be set in. Because I was going to use the bottom position, I moved the angle adjuster down after taking this photo. This angle adjuster is why you can’t just drill holes in your existing lever and have it work smoothly.

The MSR has two limitations:

The install

The first thing I did was lube the cable, which dropped the pull by 15%. I used a cable luber with Blaster Silicone spray after the saga of the unusable PJ1 and Boeshield T-9. You want to flush the cable out thoroughly, with lubricant pouring out the lower end and carrying grit with it.

My starting lineup on the left handlebar looked like this:

BTW: For any bar-mounted device, you want to make sure it has a “split-perch” so you don’t have to slide it off the end of the bar. Since all my stuff was split perch it made rearrangement fairly easy.

Here is the finished lineup on the left side. I positioned the MSR to allow two-finger use and it feels good. The horn button is further away but still reachable:

The exposed cable end is not good since I often ride or transport in heavy dust conditions. I will probably just wrap a bicycle inner tube around it with some wire ties. Sano!

I could actually fit the kill switch in, but moved it over to the right side instead. It is crammed in between the throttle and brake master cylinder:


Seat issues and upgrade options

As Frickin’ Jim points out in his review of the classic XR250R, modern dirt bike seats are not designed for comfort: link to video quote. The seats are minimalist, with assumptions that the rider is going to be racing and standing. Also they look sleek and stylish. None of this helps the long-distance trail rider.

The typical advice is, stand up. Well, I stand up all day at a sit-stand desk in the office. But I can’t stand up for longer than a few minutes on the pegs. And it’s just not practical for all-day backcountry riding carrying a heavy pack.

When I mountain bike, I have minimal discomfort even riding 6 hours on a thin saddle. But dirt biking can be painful, especially in hot weather wearing full armor.

Butt sensitivity depends on many variables like individual skin toughness and pelvic structure, age, weight, smooth vs. rocky trails, etc.

Before we get to seat options, here are a few butt options:

[New, March 2018] Comparison of Skiveez and Baleaf briefs, turned inside out to show padding:

^^^ Obviously the Baleafs are designed for the shape of a bicycle saddle, where the sit bones are right at the edge of the saddle. The Skiveez are much wider and the material is pleated. I would estimate the Skiveez padding is about 2-1/2 times as thick as the Baleaf.

Now onto the seat upgrade options...

What you need is simple: more surface area under your sit bones. More surface area equals less pressure on your sensitive skin. The bicycling community actually fits seats to butt dimensions: “It’s difficult to imagine a cyclist these days buying a bike saddle without knowing his sit bone measurements.” SQLab

Courtesy of SQLab

For motorized trail riders, you need a wider seat and typically a softer foam. Here are the main options by increasing cost.

Guts: Foam to fit stock cover = $90

They have soft, medium, and hard foam but the width does not change.

Seat Concepts: Foam and Cover kit = $175

Seat Concepts seats are constructed using a foam material that is a much higher quality than OEM seat foam. Our proprietary formula provides a more plush and active ride, while still offering the necessary amount of support. Our unique comfort shape maintains a similar contour to stock at the front of the seat so the rider’s legs are not spread farther apart, but tapers out towards the mid-point to distribute rider weight over a greater area.”

The CRF230F seat is about 9-1/8 inches wide. See project below for install details.

Fisher: Ship them seat = $300

If you want more comfort from your stock seat, then the key is added width which provides more support for a better foam density. Stock covers need additional vinyl for trim with widened seats. You have your choice of vinyl for this trim or a new complete cover.”

“Riders 180lbs+ are usually equipped with medium foam. The 'extra soft' option will remove more OEM/stock foam and be replaced with a second layer of our foam. This is often a soft/medium combination adding $20.“

They make CRF230F seats at 10 inches and 10.5 inches wide:

Avoid local upholstery shops even those claiming a motorcycle speciality: These good folks typically don’t understand the ergonomics of street bikes and have no clue about dirt bikes with vertical acceleration. I wasted hundreds of dollars on a custom seat built of open-cell foam. The artiste had photos of his award-winning seat designs on the walls, but he did not know how to provide function. I had to completely rebuild it myself as documented here.

Above: 27 March 2018, 7 October and 10 December 2017 by JXG

Link to this section:


Seat Concepts upgrade and results

I decided to try the Seat Concepts option after noticing that most serious backcountry riders have them on KTMs, Betas, and Huskys.

Seat Concepts provides helpful advice on stapling the cover: “The best option for a staple gun is Harbor Freight's Wide Crown pneumatic stapler. (Item number 68029). We recommend T-50 stainless steel staples, and it is important that the depth of the staple not exceed ¼-inch.” page

There is a huge difference in width, from about 7 inches up to over 9 inches. Visualize your sit bones on the stock seat at left and the foam at right:


The first step is to separate the old foam from the seat pan:

Next you use spray adhesive to carefully attach the new foam to the stock seat pan.

Since dirt bikes get wet, you want to cover the foam with the included plastic to help keep water out of the foam.

Then you put on the new cover:

This is easy and fun with the staple gun:

RESULTS: Big difference! Compared to stock, the seat now feels like the bench seat in a big pickup truck. I still use A&D when riding multiple days in a row, but this seat has made all the difference in riding comfort.


Above: 10 December 2017 by JXG


A low mirror under the handlebars

Mikerbike looked at my mirror above and commented: “A Tusk dual sport fold up mirror ($9 RMAM) sold for right side use can be mounted on the left side under the bar. Your waist is not as wide as your shoulder so it can be further in under the hand grip where it is a lot further from getting whacked by off road obstacles.” (post)

Fernacticus added: “I have been running a mirror mounted under the bars for some years, It's the only place that the mirror will survive a tumble. The first ones I made used an old Bark Buster type mount and a second hand road mirror. Cut the stem to length, run an 8mm die down it to put a nut on the end and adapt to the space you have.” (post)

This gave me the idea to try a Ken Sean mirror mounted underneath like this:

After taking this comparison photo, I removed the top mirror since I’m not really into the Mod look (Sting in Quadrophenia).

I will be trying the low mount for the next few months.

My only reservation about this arrangement is whether in a bad fall / crash rocks or brush could drive the mirror up into my hand. I will try moving it over a couple of inches.

UPDATE 28 March 2017: I am liking this mirror but the mount has to be very tight on the bars. I drilled out the handlebar clamp to 1/4-inch and replaced the bolts with M6 x 40mm socket head cap screws and put lock nuts on the ends. The clamp is now super-tight without stripping out the threads in it.

Update 21 May 2017: I am liking this mirror position even though it can be bumped by my knee (below). Notice the neutral indicator light above the chainsaw rack.

Above: 21 May 2017, 7 January 2017 by JXG


Uncorking the CRF230F: Current state of the art

“The most popular, and the most essential CRF230F mod: Uncorking / Jetting. This is such a simple task, yet so many people shy away from it! What is it? Uncorking/Jetting is removing the “plugs” that Honda intentionally puts on the bike to dumb it down. - Frickin’ Jim

“As most everyone knows, (thanks to Mike Coe, VortecCPI, Adnohguy, and BTR) we basically have the stock 230F jetting down to a near science.. 118/120 Main, 45 Pilot, needle clip in 4th groove from top, 1.5 to 2 turns out on fuel/air screw, snorkel removed, exhaust uncorked, BBR/ProCom CDI.. the stock 230 rips with these simple modifications and adjustments. - Falcon 1 post

Like many things CRF230F, uncorking has gotten a lot of work over the years. The TT jetting thread is 39 pages, but you don’t have to read it. The key updated items have been pulled out below. The main thing to know is the Honda “Power Up Kit (PUK) is no longer considered state of the art. You can do better for cheaper. Minority report? The Power Up Kit still has its fans as in this post

Here is the current state of the art with some crowdsourced details and gotchas. The definitive illustrated guide is by Ramz.

JIS screwdrivers for Asian phillips fasteners are good, especially to avoid stripping carb screws

Float level is very important. Before removing the carb, check float level with clear tubing connected to the drain / vent line: “Optimal float level is at the mating seam where the float bowl mates with the carb body. Low fuel level in the bowl could cause a lean mixture; likewise.. a high fuel level could cause a rich mixture. Spot on would be at the top of the float bowl mating/gasket surface” - Falcon 1 post

Remove the carb and set float level if needed: see Float level measurement and adjustment for the procedure

“If your bike truly runs better with a 130-132-135 then your float level is off! (Very common problem)” - Adnohguy post

Needle. Install a stock '03-'05 needle 16012-KPS-901 Partzilla

“The OEM 2005 and older needle IS the superior needle to ANY OTHER NEEDLE” - Adnohguy post

If you have a 2005 or earlier model then you already have this needle, unless the PUK has been installed. The presence of a 132 main jet is a PUK tipoff.

Needle clip in 4th groove from top

The needle comes with a needle jet. Should you replace it?

If you have a 2007 or earlier model, you can follow the Ramz procedure

If you have a 2008 or later model, see Changing the carburetor needle on a 2008 and later model for some modifications

Main jet depends on elevation

Pilot jet. 45 Pilot Jet (aka Slow Jet) 99103-MT2-0450 (Partzilla)

Kouba fuel screw is a very worthwhile addition so you can adjust the idle mixture while the engine is running. Ramz explains how to do this.

Verify correct float level after reassembly using tubing:

“Not sure how the floats got bent, possible from bending tab to set float height a few days ago. Also, it's entirely possible the floats were bent the last time I tried to adjust the carb, and this contributed to not starting/running rough.” - Falcon 1 post 

“When you put bowl back on carb, it is very easy to mis-align floats” - BTR post (Note both these posts refer to PWK carb, but still relevant)

Mine was leaking recently because I bent the tang because I was not paying attention when I installed the bowl after a cleaning.” - 1gr8bldr post


Mods to go with the carb mods above:

Air box baffle removed: this is the main restriction

This will make the engine run lean so make the jetting changes above first (ref)

Backfire screen?

“Mike Coe leaves the screen in because he could find no gains with stock or mildly-modified engines.  Frank Nye takes the screen out.” - VortecCPI post

“There is no benefit to removing the air filter box screen on a stock 230f [or 150f]. Neither bike uses enough air for it to make even the slightest difference in power. (Or jetting). Example: my 230f with over 13:1 compression 262cc with a 30mm xr250r carb, ported and a huge custom cam has a bone stock air filter box with all three Factory screens in place.” - Adnohguy post

Rubber boot around the airbox opening? Removing it provides 20% more area but this only changes the calculated velocity from 10 to 8 feet per second: not significant - VortecCPI post

Keep in mind that the engine needs some back pressure to function properly. Removing all resistance to airflow is NOT the objective here.

A high-flow air filter like a Twin-Air, etc. is a good addition

Any exhaust

But: “The EO Outlaw system likes a 110 main, as did the EO PoweRing.  These exhaust components seem to have had little or no impact upon the slow/pilot size.” - VortecCPI post

If stock exhaust, exhaust diffuser removed or modified: see Ramz

BBR/ProCom CDI box is probably the best bang-for-buck upgrade you can make for responsiveness. See ProCom CDI and Dial-A-Jet upgrade for some quotes on the ProCom.

Fuel screw adjustment. “Any time the float level, the pilot jet or the needle position has been changed, the idle mixture screw [fuel screw] should be adjusted for the fastest idle speed, then set your base idle speed where you like it best.” - Adnohguy post.

The process is explained by Ramz with reformatting here

You also want to check throttle response. See the PWK procedure for this second step.

An easy and precise technique using a tachometer

“I use a flex driver that stays hooked up to my modified screw. This way, I am not going by memory but rather turning it back and forth listening. Even then I had no confidence so I bought a cheap tach that reads in 20 increments. Now I just watch the tach. Much more precise in that I can now dial it in better than by ear. Most cheap tachs read in 60 increments. But...... this is for the given, elevation, temp, etc. It will not be correct if done in the summer versus winter. This is the whole point of the screw being set where you have a range of adjustment, keeping you in the parameter for winter or summer fine tuning in the field” - post

Replaceable battery model with 10 RPM resolution: Amazon. Note this uses the somewhat unusual CR2450 battery; keep a spare around

Reinstalling the carb. The carb must go completely into the intake manifold boot. Otherwise you will have air leaks. It should look like this:

^^^^ It takes a lot of force to get the carb to snap into the boot.

Above by JXG: 26, 12 December, 7 January 2017


Float level measurement and adjustment

“Proper float level trumps ALL jetting you may be trying to do.  It is the FIRST thing you should check before changing anything. ....  It is ABSOLUTELY CRITICAL!” - VortecCPI post

The tube test showed my fuel level was low, about 5 mm below the fuel bowl gasket. Why does this matter? The Venturi “pump” of the carb is designed to lift fuel about 15 mm to the carb throat where it is atomized. By lowering the fuel level another 5 mm, I’ve added 25% to the lift needed and made the engine run lean. How lean? Significant but unknown. There is a curve somewhere.

Adjusting float level can be challenging and even contentious: post. I worked through this post and tried to figure out what was going on.

First off, where is the float level gauge to be placed? The Book (Honda Service Manual, p. 5-14) says:

“Set the float level gauge so it is perpendicular to the float chamber face...”

“and in line with the main jet”

Ramz explained this in the post above and here is what it looks like:

That’s the easy part. Now the valve timing, which is harder.

The Book it does further say: “With the float valve seated and the float arm lip just touching the valve, measure the float level...”

Here is the operating sequence that I see, with the carb upside-down and the floats facing the sky:

  1. The wire bail lowers the float valve towards the seat
  2. The valve stops moving: it is now seated
  3. The float arm lip keeps moving a tiny bit
  4. The float arm lip touches the spring loaded part of the valve
  5. The float arm lip compresses the spring loaded part of the valve

My interpretation is that the measurement is performed at #4, not at #2. If this does not make sense, reread the Book above: seated (#2) and touching (#4).

Identifying the exact moment of #4 is not easy. You need to get an angle where you can see around the wire bail to observe the tiny gap between valve and lip.

Here is one way to do it:

I did this a few dozen times and finally decided that the valve was activating about 1 mm too soon... sort of. Maybe? But this interpretation matched the independent evidence of the tube test, which was good. So I bent the lip upward a hair (away from the carb, raises the float).

This is not easy, because the steel is springy and you have to estimate how much to overstress it. To avoid misaligning the floats, I did the lip bending with a small screwdriver in the center where the structure is strongest:


Filled the bowl with gas on the bench and... about 3 mm high now. So I bent it down a hair (towards the carb, lowers the float). Filled again, and close enough!

I opened the bowl yet again and measured: 12.5 mm and the lip just barely kissed the valve. It was subtle. It was beautiful. It was a pinnacle of mechanical design. Who’s up for EFI?

BTW I tried the technique of blowing into the fuel line, but the results varied with pressure. It is too easy to pop the valve open. I could not get consistent results.

Some have argued that the float should always be parallel with the edge of the fuel bowl. From this perspective, you don’t need a gauge. You just need to make the float parallel by eye and then adjust the lip so the valve is right.

Here is parallel, or as close as I could get to it:

This is what 12.5 mm looks like on my carb:

They are not that different. I would guess that on some floats, parallel works out to be about 12-13 mm... or close enough.

“As you found out, the gauge gets the floats in the ballpark, but the wet-set dials it in” - k-moe post

Above: 29 December 2016


Changing the carburetor needle on a 2008 and later model

The needle retainer mechanism has changed and the Ramz procedure needs to be altered slightly for 2008 and later. Here is the change, courtesy of the Honda Service Manual, p. 5-11:

Because after 2008 the pins face in opposite directions, the link is locked in place. You can’t simply remove the link spring and slide the link out as Ramz shows. You will need to remove the throttle drum, which probably means this procedure can no longer be performed with the carb on the bike.

Below is the slide mechanism. The link arm locking screw has been removed with a JIS #2, so the arm now pivots freely. I’m getting ready to remove the spring, unaware that this is no longer necessary:

Even with the spring removed, the link is trapped. You need to pull out the throttle drum to release the whole assembly:

I decided to remove the needle retaining screws with the slide in place, an alternative technique described by Ramz. This protects the needle from being bent while the screws are being removed. I used a JIS #2 screwdriver:

Note above I am holding onto the link with pliers to keep the slide from turning. On a 2008+ model it is likely that the link and link arm could be left connected, and just flipped back and forth to allow access to the screws.

With the needle screws out, here is the whole assembly. Notice how the link is trapped between the two pins. For 2007 and earlier models, the needle retainer pin points the other way so the link slips off when the spring is removed. Again, it’s not clear that the link even needs to be disassembled for a 2008 like this.

With the needle changed out, reinstalling the needle holder. The needle is hanging out the bottom so this has to be done very carefully:

Above, I was able to slip the link on but it should probably already be installed at this point.

The link and spring reassembled:

Now reinstall the throttle drum. First, don’t forget the plastic washer that goes on the shaft between the link arm and housing. You also need to clip the circular return spring into position. Note how the spring clips onto the upper right, above the stamped “G”:

Getting the screw into the shaft can be quite challenging. Remember that the top of the shaft is not threaded. The threads are actually on the bottom. If you can see threads on top, the shaft is upside down.

I slackened the circular spring to a kind of half-cocked position, like this on the left:

Somehow this let the shaft go further in, allowing the holes to line up and the screw to go in. I then pulled the end of the spring to full tension by hooking it around the carb body where the pliers are pointing: above right.

Make sure that everything is working smoothly and then put on the cap. This “pump-jack” mechanism, the powerful spring, and the push-pull cable mechanism all produce the snappy throttle action of the CRF230F.

Above: 31 December 2016


Carb tuning techniques

CRF230F carb is Keihin PD9CF.

Tuning by feel

VortecCPI post: “For those of you who have not seen this I suggest you read the tuning section in this manual:

“The test is started with the engine running at an rpm high enough to ensure that it is “on the cam.”

Tuning on a hill: Powroll method

Posted by VortecCPI:

“These jetting specifications are designed as a rule of thumb. They are in no way absolute. Variations in air density, specific gravity of fuel, altitude and other engine modifications play a large part in jetting. It is the responsibility of the owner to determine proper jetting for their engine.

Plug reading doesn’t work. Revving the engine while it’s sitting in the garage doesn’t work. Other than Dyno testing, the steps below are the only way you can consistently jet your engine.

1. Find a gentle slope that you can ride in 2nd or 3rd gear. Look for something that will put a decent load on the engine. This will be your tuning test area.

2. Make the recommended jetting changes. Always start rich and work leaner.

3. A basic outline of which jet is active at a particular throttle setting:

Pilot Jet = 0 to 1/4 throttle. Needle = 1/4 to 3/4 throttle. Main Jet = 3/4 to Full Throttle.

● Changing the Main Jet size won’t affect how your engine idles or runs at 1/4 throttle.

● Engine RPM isn’t what determines which jet is active - only throttle position does this.

4. Start and warm up the engine, then ride your ‘test hill’. Any point where you feel the engine stumble or hesitate indicates a rich condition. Note the throttle position and modify the corresponding jet (1/4 to 1/2 throttle = leaner needle. 3/4 throttle or more = leaner main jet).

5. Only change jetting by 1 step at a time, and 1 circuit at a time (don’t change needle and main at the same time). Re-check after every change.

6. Once the engine runs smoothly throughout, you’re jetted!

If you ever notice an abrupt change loss of power, or engine sounds changes, shut it down.”


Tuning by plug chop

“You can not just pull the plug after riding around. There is a procedure and it requires sustained WOT run time in a high gear preferably up a slight incline. Then you kill the engine, pull the plug, and examine the electrode at the very bottom of the plug.  This can be done using a good light and good eyes or magnifier or you can chop the plug. Today's non-leaded and oxygenated fuels do not color plugs like the old days.” - VortecCPI post


Jetting adventures 2016


Important: Until 12/31/16 my float level was too low and the bike was running lean. This should be kept in mind as you read the following. Also the plug tests were not performed properly.

Purchased used in CO (6500’) in 2014. Carb never touched until Oct 2016 when the status was:




10/14/16 Chami test rides at 6600 ft


10/15/16 Chami test rides at 6600 ft


10/21/16: Trail ride: It ran fine with the Intelajet fitting filed down.

10/23/16: Removed airbox ring (boot) around opening, exhaust diffuser. Could not really tell any difference, including noise level. Reinstalled both.

11/5/16: Diffuser in, seems quieter

11/11/16: Stopped on the trail and removed the diffuser: with the ProCom CDI I really noticed that it seemed plugged up and less free revving.

12/31/16: Changes to conform with Uncorking the CRF230F: Current state of the art 


Jetting adventures 2017

Lessons learned or relearned:

7/28/17: With PowerBomb now installed and 112 main installed in June, need to check fuel screw


Ignition timing mod by changing flywheel key


ProCom CDI and Dial-A-Jet upgrade

VortecCPI has a very interesting discussion of low compression engines and how more throttle response can be gained. Key quotes:

Procom CDI is HUGE Bang-for-the-Buck on this low-compression engine IF you ride slow short tight technical.  These engines respond in the same way low-compression engines did back in the mid-70s to mid-80s.  We used to dial them up from ~8 BTDC to 16-20 BTDC (total of 36-38) and the difference out of the hole and up to 60 feet was quite noticeable.” - VortecCPI post

“I believe with the Dial-A-Jet and Procom CDI the bike is a changed machine.  For an investment of $150 (Dial-A-Jet and Procom) you can't go wrong IF you are an off-idle and low-mid torque junkie like I am.” - post

“I'd have to say the big difference with the Dial-A-Jet is how the bike pulls from the mid to the top.  It comes out of turns very, very hard now and occasionally pulls the front tire slightly off the ground as I exit a turn.” - post

“That 12-tooth c/s combined with the Dial-A-Jet and Procom CDI makes the little 230 grunt like a big block tow truck engine.  I'm positive the smaller 112 main also made the throttle response far crisper.  The combination of all these factors just plain works.” - post

Dial-A-Jet Review

This thread has some dyno results that show the DAJ / IJ work but as VortecCPI points out it is really the sensation of throttle response that matters and a dyno does not measure that: thread

ProCom CDI box


The IntelaJet

On my KTM 300 in 2008-11. I ran the Dicks Racing Keihin 36 mm Carb with the oval bore + Intellijet and it was almost like FI. Because you set the baseline jetting Super lean for clean off idle response and the Intellijet fills in the more throttle you give it. It was good for no changes +-4000 ft. Then you just adjusted the dial to lean it out if needed. I never felt the need to change any jets once the baseline was set. I ran Motul 800 at 50:1 and the plug was a perfect chocolate brown always.” link 

The IntelaJet is a more expensive version of the Dial-A-Jet, with probably 5 sizes (not digits) of main jet adjustment. It is also easier to adjust because it has a remote control dial.

The injector goes just upstream of the carb. Placement can be a bit tricky on small bikes because there is seldom extra room. As the diagram below shows, the injector should be at 90 degrees to the airflow for maximum Venturi effect across the injector. The Venturi effect of air movement is what creates suction to pull the gas up:

(Diagram courtesy of Thunder Products)

I looked at various options for placing the injector. The only real location was into the rubber intake boot.

The boot is a common location and not a problem.

But the steepness of the boot meant the injector was going to be at a bad angle.

Using 1 mm aluminum sheet, I made a sort of "ski jump" mounting bracket that angles the injector. The bracket is held to the boot with two sheet metal screws.

All penetrations of the boot are sealed with silicone.

The injector ended up well-centered and close to a 90 degree angle to the airflow:

Gas supply, round 1. Thunder Products sells a deep well fuel bowl nut that is claimed to reduce the reality or potential of starving the main jet. I bought one and found a few difficulties with it:

Gas supply, round 2. I gave up on the bowl nut and tried the option of connecting to the drain line as shown in the instructions. This produced unusual behaviors on the CRF like surging and gas leaking out of the airbox.

I finally remembered what I had already figured out when I tried the IJ on my AJP: the carb drain is not just a drain... it is also a vent that needs to be left open at all times.

(Even on models where the drain line is not a vent, I would not give up the ability to easily drain the bowl of E10 gas, etc.)

Gas supply, round 3. I tapped directly into the float bowl. Center rear, so the line runs away from the exhaust manifold and starter.

But the fun was still not over. The CRF ran out of gas on uphills: see Jetting Adventures 2016.

It turned out the float was hanging up on the tiny lip of the brass fitting.

I filed this down so it was completely flush and the IJ finally had a gas supply that worked.

Side note. A lot of people get frustrated with taps because the sets never include the one instruction you need to know. The key to using a tap is backing it up to clear the cuttings. Each time you turn clockwise a quarter-turn, stop. Now turn backwards a quarter-turn to clear the cutters. Then go forward again.

Routing of the fuel supply line and the remote control tubing (top).

I included a one-way check valve in the gas supply line. “For even better throttle response” it seemed worth a couple dollars.

IntelaJet remote control installed on the gas tank:

UPDATE December 2016: The blue polyurethane (?) fuel line runs through a high-heat area just inches from the exhaust pipe. The kit includes an insulating sleeve to protect the line where it comes out of the fuel bowl:

Be sure to use this. A leak could start a fire and/or leave you stranded.

IntelaJet jetting: 110 nominal for home elevation of 5000 feet

UPDATE, December 2017: With the OKO carb change I removed the IntelliJet. It never really seemed to do anything significant. Not recommended.


Water crossings

Having the engine die in water is generally not a good thing. It can result in anything from wet boots to the bike being dropped and flooded. In the high country stalling can be the first step towards hypothermia if you fall and get wet in an alpine creek.

The primary limit of course is the opening at the top of the airbox. Waves will swamp this from several inches below. But there is another item that will stop you long before you get that deep: the carb bowl drain line.

The carb bowl drain line is more than that. It is also an overflow and most importantly a vent. If this hose gets blocked by water for more than a few seconds the engine will start to cut out. Pinch the line and try it. On my KLX250S and AJP, I’ve found this happens from either submersion or even heavy splashing.

The traditional solution is called a “T-Mod.” It is easy to make one.

A high snorkel serves as a “vacuum breaker.”

The drain line is 0.23 OD x 0.12 ID, basically around 1/8-inch.

I used a Rainbird irrigation T-fitting placed 2.5 inches from the carb:

These fittings are cheap and designed to languish in gardens, so they are not very tough. I broke one during installation and will be looking for something tougher.

The 1/4-inch vinyl snorkel runs up along the crankcase breather, then past the air box opening, and ends under the seat.

The overall plumbing should form a “Y” shape. Make sure everything drains down, so that fuel or water can’t form a blockage.

We’ll see how the vinyl holds up. It should probably be replaced with Tygon which is rated up to 165F.

If you use a mechanical rear brake switch, you may want to seal it up with silicone then fill the inside with dialectric grease (Amazon) to keep out water. I did this with a 3 ml syringe.

Remember that even with seals the wheel bearings, linkage bearings, and swingarm bearings are all vulnerable to water entry and rusting. If you anticipate water crossings, make sure the grease is waterproof, thick and fresh. Consider servicing after submersion. See Rear suspension inspect and grease for how-to.

UPDATE: At some point the plastic “Tee” broke as expected. I replaced it with a “Legines Brass Hose Barbed Tee” which has three ⅛-inch barbs from Amazon.


Exhaust upgrade options


“My experience with fenders that block air flow to engine is different but maybe it is the terrain. e.g. I have Vapors on most of my bikes and while riding one with a large watercooled type of fender on a long steep climb in the mountains I saw cylinder head temps at the spark plug of over 400 degrees.” post

“I also have a Vapor and temperatures at the plug can get very high when riding in the summer on slow technical trails, even with the mild stock compression ratio.  I have seen temperatures over 350 and, at times, close to 375 under severe conditions.  Conventional motor oils begin to break down near the 400F mark.” post

The PowerBomb header

The stock head pipe is a significant bottleneck: post.

FMF PowerBomb, $170 CrfsOnly

Manufacturer statements:

“It was your work along with Powroll's input that made me try the FMF head pipe and the results were quite amazing.  The FMF head pipe resulted in a BIG gain right in the middle and all others who have tried it have concurred.  This is counter-intuitive to the auto world where we like long skinny headers for tow and RV work and short fat headers for high-RPM work.  In the case of our little two-valve engines the larger head pipe seems to net gains across the entire engine operating range.” - VortecCPI

“The fmf powerbomb I installed {with a perfect fit i might add !} on my 2005 450x totally smoothed the power! The 450 is so fast "out of the box" I wasn't sure if anything would even be noticed! I was wrong,power delivery is just sooooo much smoother and it also "tamed" the exhaust bark, which at 53 years old I was ready for more power with less noise ! It also seems that what they say about less noise tires out the rider less is true ! I can go rip out a 60 mile loop in mendocino national forest and feel great when I'm done, not exhausted from the racket!” - review at RMAM

Modding the OEM Muffler and Removing the Swage on FMF PowerBomb - baglock1 post

PowerBomb install

I found the old header could be removed without removing the muffler, but the new header could not be reinstalled. Removing the muffler only takes a few minutes. I used JB Weld Red silicone on both joints.

Note the PowerBomb is a tuned resonator chamber. The pipe diameter does not change. The pipe connects to the chamber through a single hole as shown in Patent 7510050:

Stock header without heat shield is 1.48 lbs. I forgot to weigh the PowerBomb but it felt lighter.


Side by side:


Heat shield installed with hose clamps:

After this photo was taken I added 1-inch sections of 1/2-inch aluminum channel to hold the heat shield slightly off the pipe. This will keep it a bit cooler.

RESULTS: On my standard street test I did not notice any difference in response at all. The exhaust note seems a little different. For noise level see Sound level measurements.

First trail ride: Not a dramatic increase, but there seems to be a slightly improved "response zone" in the upper midrange.

Above by JXG on 28 July 2017


EO Outlaw system

“As discussed in numerous threads, this sucker is LOUDpost



The EO header is an even larger diameter header then stepped larger yet, and made a very easily noticeable difference just by bolting it on. Night and day. No question at all. I was pleasantly surprised and could not believe the difference.” - Adnohguy

“The last thing I did was get one of Frank Nye's awesome Outlaw exhaust systems.  I know from experience how well a properly-designed tuned exhaust system works so I was very hopeful for good results. Not only did I save two pounds of weight and get more low-mid and high-mid, I also got a bunch of top end power.  I swear it feels as if I have more CR, more CCs, or more cam.  I got WAY MORE than I expected with Frank's pipe. While most of the time the bike is doing slow short tight technical work the pipe really is a charm when dealing with fast long open areas or when I need to hold a gear longer.  When Frank says it could be the difference between being #1 and #2 at the end of the day I believe him.” - VortecCPI

Frickin’ Jim shows and discusses the “unique” Outlaw system


Sound level measurements

“Sounds of less than 75 decibels, even after long exposure, are unlikely to cause hearing loss. However, long or repeated exposure to sounds at or above 85 decibels can cause hearing loss. The louder the sound, the shorter the amount of time it takes for NIHL to happen.” - NIH

Like many I bought a used CRF whose exhaust diffuser is gathering dust on a shelf or in a landfill post. Note: There is a still a spark arrestor screen even if the diffuser is removed.

Ramz on diffusers page

In 2015 I tried the “Bikers Choice Exhaust Pipe Baffle 1-1/2" OD Steel 64301 492611” Amazon. Later I took this out because it did not seem to make any difference in either power or noise level.

Then in 2016 I put it back in but it seemed to greatly constrict the now-uncorked bike running a ProCom CDI. The bike would just not howl up test hills. I compared it back to back with open muffler and the difference was very noticeable. Again, since it also didn’t seem to lower the noise level much so I left it out.

Finally I got around to measuring the difference.

I followed the procedure in the USFS “summary of the SAE J1287 JUL98 stationary sound test procedure” document: 

There is no RPM listed for the CRF230F so I held the throttle at around 4000 rpm as measured with a “KEDSUM Upgrade Version Waterproof Hour meter Tachometer” Amazon which has a precision of 10 RPM.

This is the test setup. Nexus 7 2013 tablet running “Sound Meter” app at a distance of 20 inches from the exhaust. This is not a calibrated device:

Here are the results:

This data, if it is correct, suggests that on the SAE J1287 test:

I should have used an app that actually exports numerical data but the graphs are pretty clear. I cannot explain this. I would have expected a visible difference.

On the other hand just 3 dBA is a doubling of sound pressure and most of the time that cannot be perceived: page.

Anyway... this is why I always wear 32 dBA earplugs whenever riding.

UPDATE Sept 2018. A reader asks whether these small differences are significant given an uncalibrated device and not controlling for background noise level post.

Here are the curves.

CRF230F stock header no baffle:

CRF230F stock header with baffle. It does look like it idles a bit quieter.

After I added the PowerBomb header, no baffle:

PowerBomb header, with baffle:

Here is my 2014 Beta Evo Sport 300 4T, with Spanish Fly spark arrestor screen:

While this bike seems quiet when plonking around at low throttle, it really is not quiet overall.

Above by JXG on 29 July 2017, updated 15 September 2018


[*] Is it possible to quiet the CRF230F while maintaining power?

“Our exhaust is noticeably louder than stock but not ridiculous. We have neighbors too. Unfortunately, power and sound go hand-in-hand - don't let anybody tell you different.” -- BBR Motorsports FAQ

Theory: Tunable baffle

Kouba insert

Giovanni: “The total area of the holes in the can should match the output cross-sectional area of the baffle (our baffle external OD is about 35 mm, but I'll take actual measurement). So I'll start with the "plug" located in the innermost position (toward the engine), leave open a number of holes to match the outer baffle area, and cover the rest of the holes with a layer of "rock-wool" (or whatever you call it - I mean the white type good for 4-stroker silencers). The idea comes from Vance & Hines:

The other thing I'll work on is the "plug" at the end of the can: I'll start with the solid plug positioned perpendicularly to the exhaust flow (the standard position, that is), then at a 45 degree angle (as per the links posted yesterday), and then drilling two tiny holes in it (I don't know if that additional area will make a difference).”

New study on measuring sound level with smartphone apps 

Giovanni has ordered this post

The above is NOT available in the US

This one appears equivalent and is available in the US:

More photos and cheaper, not stainless

Wrapping the baffle:

BTR: “Too much tech talk on baffle. As far as any baffle mod on stock 230 muffler -- all will kill any extra power you may have. For me if I had to deal with street quiet, I would keep the stock baffle. When dirt bike riding remove it to make more power as any baffle even with mods is a power robber.” post

Ramz has photos of the stock diffuser and notes that “the spark arrester and exhaust diffuser are sold as an assembly”. However, the parts diagram only shows the spark arrester:

Above by Gio_crf_tt and JXG on 16 September 2018


Engine mods

All the uncorking mods above can be done without getting into the oil zone of the engine. Engine mods are the next level. The payoff is big, the work is big. And it is all an integrated system so for real improvements you can’t just do a little here and there:

“Think of the WHOLE package. Proper exhaust  / airbox mods / jetting / compression / headflow / induction. Match all for same purpose and you will be happy.” - Teamrude post

“There is no substitute for displacement. Get a Wiseco or Wossner 11:1 piston in 67mm and get with Terry Miller [Teamrude] for a thin copper gasket and one of his cams that he recommends for your riding style. You will not be sorry! Building one of these bikes is not cheap so you sure don’t want to do it twice. These are PROVEN set ups so I highly recommend.” - Titanman post

What is the real stock compression ratio? Honda claims 9.5:1 after 2005, which (according to Adnohguy) Terry Miller says is really 8.7:1 post


Displacement is displacement. Cams are different and their geometry produces very different behaviors--which need to match your riding style. In turn, the cams often place demands on other things like compression ratio. It’s all a System. Terry Miller of Miller Vintage Cycle reviews the proven options...

Teamrude on 21 August 2016 - post:

“I will try to make this easy as hear boatloads of questions on these and others. On top of that Web Cams sends their customers for cam recommendations.

There are 5 basic cams commonly available for crf230. I really don't count goofy aftermarket like HotCams etc so bear with me.


Web Cams has 2 standard commercially available cams. Most will know them. 40-402 and a 89A. 40-402 is a amazing tiny cam. And 89A is a big jump up BUT not perfect for most builds. Here is rundown on those 2.

1. 40-402 is a massive low-end torker cam YET has better mid to top than a stocker cam. Tells you how bad your stocker is!!!!!! Awesome bottom end power and works well with stock or moderate modified stocker. Too small for EO's 251cc big bore or 254 stroker. Great cam for Uber tight trails etc.

2. 89A is based off of a older XR200 grind from WEB. It does have some legs but kills bottom end most love the 230 for. It does work with 251 big bore or 254 stroker but there is ways to improve.

3. Problem is there is a HUGE area between #1 and #2


Megacycle makes a X-1, X-2 and X-3

1. X-1 is wonderful torker trail cam. Bigger than 40-402 yet retains great low-end. Boost from bottom to top

2. X-2 is in a lot of ways similar to 89A yet I feel is better cam. NEEDS a decent built 230 to use. Must have compression and CC's for best results. Also at limits of stock valvetrain.

3. X-3 is pretty healthy. Of course at this point CC’s, compression and headwork with exhaust required.


Here the new ST Super torker cams come in.

1. ST1.0 is a upgraded 40-402 with a little more intake duration (needed on these) and slightly modified lobe centers. Huge torker yet will make a wide powerband even up to moderate stroker or EO 251. This is perfect for tight trail with simple Wiseco/Wossner swap for piston. Headwork is always suggested but this cam is mellow similar to stocker only better EVERYWHERE.

2. ST1.5 this is a 1.0 that has been modified to make more aggressive snappy power. Has more peak torque with maybe 500-750 less peak rpm. This is perfect for offroad trail rider who likes a little snappy when needed. Will work with stocker or 233 Hi-comp. Even a 251/254 will pull like a diesel with this.

3. ST2.0 this is good step above 40-402 or "1" Series. this still has great bottom (especially in 10:1 233 or bigger) yet really wakes up midrange and will run hard near top-end also. Nice smooth OVERALL power and will work with stock to 251/254 all day long.


4. ST2.5 This is hotter version of 2.0. Quicker snappier power. Perfect fast offroad type power. Will lug all day yet very hard midrange so if you ride "firmly" in the trails you will like.


ALL ST series will work with stock springs and guides so no real issue with these.


I am working on a one step harder ST3.0 which will be a split duration / modified lobe center verion of 89A. What a 89 should have been from start!


Best suggestion I can ever give is to TRUTHFULLY evaluate your needs. Too big and you won’t be happy. Too small and you wish for more. Aggressive when you need smooth???. Think of the WHOLE package. Proper exhaust/airbox mods/jetting/compression/headflow/induction. Match all for same purpose and you will be happy. Welcome all feedback and questions. Just love this stuff so almost any question is not considered stupid.”

Cam upgrades need compression upgrades

“If I had a choice I would take a piston/gasket (10.5:1 or more) before I threw a cam in it. Very low compression never liked larger cams yet appropriate compression likes cam upgrades (plus pipe upgrades, carbs etc prefer efficient motors). There is just no way to get any compression on stock style 230 head without a dome, that is unless you add a bunch of CC's to it. Not at shop today but I think on stroker and big bore (270cc) a flat-top was near 12:1 at .035 squish.

“Only reason ST cams were made is results everybody had with standard 40-402 and the huge jump to 89A. Nothing in between and a bunch of small improvements in dialing in cam specs was possible. Do not discount quality of Megacycle cams on 230. High quality and easy on parts also. Only issue with Megacycle was they will not let me play with lobe centers etc so you get what they make. It is very good cam as even Frank Nye at EO loves them. pretty much any cam is improvement over stock camshaft. But once again I will say you need to address compression first. Virtually any motor I build starts at 10:1 as anything less is just a Briggs and Stratton.” - Teamrude post

“Just listen to the advice of Wiseco or Wossner. The combustion is large (22.5-23 cc on all I tested) that even if you had zero squish you would be under 11:1. Plus zero squish does not work!!!! .030 is about minimum on these and stock piston sits from .030-.035 depending on year and "stacked" tolerances. Use wiseco or wossner and either a .020 solid copper or 1 layer of stock gasket to get reasonable compression. Wiseco can be had for under 100 on fleabay and ZERO reason to use stock or Pro-X piston unless running fuel like 83 octane. - Teamrude post

Rider results

ST2.0: “Keep it simple, wiseco/wossner (65.5-67mm) thin gasket, 40-402 ST-1 ST-1.5 and if doing open area a ST-2.0 is possible. Pro-Com box and if possible have a little work done on intake port of head. Even with uncorked intake exhaust it is dramatic change in power. Watch Frickin’ Jim videos 7, 8, 9 shows difference AND you can hear and watch motor run.” - Teamrude post

“It’s a really great all-around cam. Prior to this cam, I’ve run OEM, 89a, and 340/402. OEM is lame, although it is probably the most durable cam out there for this bike. 89a is great on a motocross track but the low RPM pull suffers too much for technical riding at very high elevations. The 340/402 (40mc/402) makes the low RPM performance excellent, even at high elevation, though it gives up top end performance in comparison to the 89a. The ST2.0 I run is the happy medium between the 340/402 and the 89a.” - Frickin’ Jim site

ST2.5: “Love my 2.5 with the 67mm Wossner and ported intake from Terry. The bike is a absolute torque monster and will climb Mount Everest! I run 93 octane and in this summer heat hear no pinging even with the thin copper gasket. I do have some RaceGas booster mixed up in my riding bag just in case this Louisana heat kicks in.” “Yes stock carb with 122 main and 45 pilot, Procom CDI's and 93 octane in both bikes. IMO the fuel delivery is just fine with the stock carbs.” - Titanman post

Key threads

Link to this section:


Clutch upgrade options to handle more power

“Looking for any help with 2008 150F clutch??? Running the engines only 225 kit and it burns through clutches, 2 DP heavy duty clutches in 1 summer basically....anyone have any suggestions or anyone with EO225 what are you running and getting how many hours? - CReffed0421

What can the OEM clutch handle? Adnohguy post

Adnohguy post:

Honda washer part number for reference post

Details of part numbers and procedure post

Above: 1 April 2018 with suggestions by On2Whls


Carb upgrades

Stock carb dimensions post

Genuine Tygon fuel line for $2/foot Amazon

For major engine mods, don’t forget a new carb--it may be the needed finishing touch as reported by jeffrow68 in particular:

These bikes respond very very well to the basic uncorking, the most bang for the buck since it is free.  Even after adding 10cc's, more compression, a better cam, better exhaust, head porting, my bike was only slightly better than the free uncorking I did on my friends bike. But, after the OKO PWK, WOW!” ref

See the complete section on the OKO PWK.

Keihin PWK D-Slide Carb

XL knockoff carb Mixxer’s upgrade post and see Builds section for his results

1980 XL 500s carb post


OKO 28mm PWK Carb Upgrade

The basic recipe summarized by Chuck ref...

Setup for CRF230F from stevethe on TT

  • For low altitude
  • 35 pilot
  • 135 main
  • 2.0 Slide
  • JJL Needle second clip from the top

  • Needle Jet: You need the short one, Sudco and JetRUs sell them. CR85s use them.

  • The jets appear identical, including ID, except for the height of the top.  The long jet extends up into the venturi by 2.5mm more than the short one. The short one is close to flush with the floor of the venturi ref
  • Chuck: "Tried tall needle jet and it did lean out the idle circuit but little effect else where." ref

  • Float level issues: ref. Chuck: “a float level 1.5mm lower than spec”

  • A 230F manifold can be used and it will point the carb towards the air boot but its ID and OD are not concentric so some blending is required for it to match the PWK. [see photos below]

Results. Jeffro68 post:

“To summarize:

I have a modified 230 with 67mm BBR piston, head porting by Terry Miller, ST2.0 cam, full EO exhaust. Running the OEM 26mm PD carb was very disappointing regarding expected results. A big investment in parts and not so big improvement in performance. After asking some fellow TTers, the carb was identified as a restriction and the subsequent testing.

1. I bought the OKO 28mm PWK from Mid Atlantic Trials. I made some adapters and fabricated a custom throttle cable. The performance gains were very impressive with this carb. I was finally realizing the potential of this engine and really happy with the improved performance.

This carb is a 2T carb and all the recommendations on TT specify going to a 2.0 slide and JJL needle with short jet needle holder.  I bought the additional 2.0 slide and needle, but somehow the original configuration with a 3.0 slide and supplied needle worked fantastic. I could not get the recommended 2.0 slide configuration to work as well, so I used the 3.0 slide. This setup works very well, it is a small carb, minimal moving parts, and the choke system does not restrict flow so is still functional (not a butterfly like the PD carb).

2. After reading reviews from the aforementioned TT members regarding the Chinese PD pumper clone [“XL knockoff carb” per Mixxer, etc.], I bought one for my friends stock uncorked 230. It was a small investment and I did all the tuning and detailing on this carb.

Since I had it in my possession, I installed it on my 230 and compared it to the OKO carb with back to back testing. It performed very well and I was really impressed. It had a little more bottom to mid compared to the OKO, but not quite as much top end. Pretty much splitting hairs comparing the two carbs, but the OKO much better quality.

I installed this PD pumper clone on my friends uncorked stock 230 as originally intended. It is a very nice and impressive upgrade to the OEM PD carb. Noticeable improvement in throttle response and overall performance. However, he only trail rides on a local farm area, so having a very reliable and proven carb isn't a big deal. This is a concern for me since I plan to really use my bike in some venues that will require some real reliability.

3. Since I liked the PD pumper carb (clone) so much but was concerned about reliability,  I eBay purchased a '78 XL250 Keihin PD pumper carb to put on my 230. I did the necessary cleaning and adjusting and installed it on my 230. Again, I got lucky and found a good working carb that only needed cleaning and a few adjustments. I really like this carb with my engine mods, and it really suits my riding style.

In my opinion, the pumper feature of this carb provides a nice boost to lighten the front end and also get the bike moving out of corners, maybe a little more snappy than the OKO but I like it.”

OKO 28mm PWK post, details, BTR mounting, and results 


More Jeffro68 results: post


Above: JXG on 10 September 2017, updated 3 December 2017


OKO 28mm PWK on an uncorked bike

A TT rider kindly allowed me to try out his build which included carb adapters and a custom cable.


Carb with custom adapters. Note enrichment knob instead of choke, plugged oil injection port (blue cap), and vent port above the logo:

Left side with idle adjustment and air screw:

Carb in place:

I could not get the carb all the way into the intake boot notch:

^^^^ Notice there is very limited clearance between the idle screw, air screw and frame member. There is more information below about how to work around these access problems.

Cable specs

Throttle end of custom cable:

Carb end of cable. Note the ferrule has slipped off in this photo:

Note this type of carb makes cable lubrication more work. Unlike the stock carb, any dirty lubricant that comes down the cable will go right into the carb slide. So I lubed the cable up before installing it.

I removed the stock double-cable system. The new cable was a bit shorter than stock. Below you can see that it did not connect at the top like the stock cable. But there was enough slack to include the plastic guide piece:

The fuel line has to be extended so it reaches over to the right side. I used some Motion Pro Premium 1/4 inch fuel line (RMAM) that I had: 6.3 mm ID x 11 mm OD. This was a bit loose on the fuel valve but the clamp stopped it from dripping. At the carb inlet it is thick enough that the clamp could not slide all the way down but this is a tight fit.

The bike fired right up with only a little enrichment. But it wouldn’t drop down to idle. The problem was soon found: the ferrule on the carb end had slipped off, effectively lengthening the cable housing. Once this was put in order the bike idled perfectly. A test ride around the block did not show any dramatic increase in response.

But the throttle cable was not done. Next, the cable housing moved and the bike idled too high or not at all. The key is very careful routing of the cable, and securing the cable housing tightly so it does not move. If turning the bars many times eventually makes the cable housing change position relative to the carb, there will be problems. The cable housing needs to stay jammed into the top of the carb. I did this with two straps and copper wire... the second time around. I now appreciate dual cable systems.

There also needs to be slack in the system so the slide will drop down to idle position. I settled on 1/2-inch of free play at the throttle tube, then reduced this to about 1/4-inch with the twist adjuster.

Boots and leaks

Neither end of the carb extends very far into the connections. So I wondered if the carb “spigot” to intake boot could be leaking: “Remember any leaks in the manifold will make a bike run like crap.” ref  You will never get the carb adjusted. Also, dirt will get into the engine.

Spraying some carb cleaner around the boot suggested leakage. I sealed the junction with black RTV which made a bit of a mess. Note that “A CB 500f intake manifold rubber” may work, but it sounds like this is for a BBR frame ref.

Gasket 2.0

When I removed the carb to check the jets, I studied the pattern of the silicone that had formed. See the needle jet photo below. It was almost a gasket. There is about a 16 mm gap and the silicone reduced it to 5 to 7 mm:


I used some 11.3 mm thick Costco floor mat to make a thick gasket. The hole should be carved out so it fits very tightly around the carb bell:

Here is the side view:

Gasket 3.0

Above, you can see how the gasket is not pressed firmly against the boot. I tore down an aluminum project box and made an aluminum ring to press the gasket into position:

^^^^ The ring sits on areas above the fuel bowl... except at the top. There I made a little aluminum bracket to rest against the oil injection port. This was pop-riveted onto the ring.

You can see the gasket is now more evenly compressed all around:

^^^^ It doesn’t look tight above, but the manifold it actually sunk into the foam about 3 mm.

Gasket 4.0: No gasket

On the second ride I went down a long series of rock ledges and the bike started acting like it was running out of gas. Looked at fuel filter and realized... the carb is disconnected!

It was time to get serious about the carb mounting. The first thing I needed to do was understand the stock mounting.

The intake manifold has a raised ring as shown by the arrow below:

This ring snaps tightly into the depression ring on the carb. This takes a LOT of force and makes for a tight seal. With the manifold off I realized that I have not been reinstalling the stock carb properly. Here is how it should look:

^^^^ Notice the manifold boot is at the limit of how far it can go on. The locating notch should likewise be completely up against the metal fin:

At this point I was thinking I needed to get a custom adapter machined that would duplicate the ring and notch design of the stock manifold and carb. I worked up the dimensions in this drawing:

Download the PDF

But then I started playing around with the OKO and the manifold. I pushed my hands together, thus producing much more force than possible on the bike. I found that for the first time I could get the OKO (with rubber hose adapter) to go fully into the manifold. Here you can see the notch and fin:

I got an idea: if I always removed the manifold then I could use silicone sealant to make it a perfect seal.

So I lubed up the connection with silicone sealant and... it would not stay in place. The thin coating of slick silicone was just enough to force the joint apart. Sort of like how PVC cement will force joints apart. So after wiping off all the silicone and actually sanding the rubber tubing slightly, I got it to stay together.

Plan B. After tightening the clamp, I reached inside with my little finger and very carefully caulked the joint with silicone. A headlamp was helpful. Not perfect but it will have to do:

With the manifold permanently attached, there is a particular reassembly sequence that works best. Typically I do this after jet changes. A ratchet box wrench is very helpful.

  1. Reinstall the slide and tighten the screws
  1. Make sure the throttle cable is OK: the slide should be fully closed
  1. Shove the carb back into the air cleaner boot
  1. Again check the throttle cable for alignment
  1. Move the carb forward and tighten the intake manifold bolts
  1. Make sure the O-ring and gasket stay in place!
  1. Tighten the air cleaner boot ring

Note the above can be done with the tank on.

So, I think the mounting challenge is finally solved:

Peripherals, adjustments, etc.

Adjusting the idle can be challenging: CW is faster, CCW is slower.

Air screw? Extremely tight and can’t be relocated.... but see below for a radical solution that works very well.

Side vent hose discussion by Chuck here

Bottom hose: remember this is an overflow hose and a vent hose to allow gas flow into the fuel bowl. So if you are going to submerge a T-Mod is needed.

Removing the fuel bowl: lift up and toward the FRONT of the carb because of the angle vent/overflow tube

For the initial setup including adjusting the air screw and idle and fixing other problems, you may want to just put the tank on temporarily.

Enrichment Knob (choke)

The OKO has an enrichment knob, not a butterfly choke. This improves airflow. On my Beta Evo Sport the knob stays up when pulled up and after a very brief period the engine is ready to go.

The OKO knob does not stay up, which is very inconvenient. In addition, with my CRF230F the throttle has to be held part way open and it takes a long time to warm up.

So I ordered the remote enrichment knob kit from Mid-Atlantic:

As you can see, there is no cable. I can build that, but how to keep the knob pulled up?

I recall cable operated chokes and throttles on old engines that would hold in position by the friction of the cable and housing. The "cable" was solid stiff wire and the housing was a spring wrapped around it. May have to use something like this. Here is an example:

Has anyone set up the remote kit? See photo


Long arm of the law: Reaching the air screw

BTR reports drilling a hole through the frame here. Seemed like classic Mexican mechanical genius so I decided to give it a try. Well, it works. I burned up a couple of bits in the process. The location has to be just right and this is very close:

Below you can see a very long screwdriver bumping into the battery box:

I was able to avoid battery box modifications by creating a custom screwdriver out of a coat hanger. This bends just enough to snake past the battery box and through the holes.

Below you can see the end turning the screw at the left of the photo and the other end of the driver at right:

I made the tip by hammering the end flat and then filing it square:

Align the tip and a bend at the far end so you can easily count turns.

RESULTS: This makes for the easiest air/fuel screw adjustment I have ever done. Even with the Kouba fuel screw, it is always difficult to keep from getting burned on the stock carb. With the long custom screwdriver and the digital tach it is amazingly easy.


Moving the idle screw to the right side

The idle screw works by pushing the slide up slightly. Turning the screw CW makes it go further into the carb body, push up the slide, and increase the revs.

The left screw is hard to reach but it can be relocated because the carb body is cast to accept a tapped hole on the right side. The article does not mention whether the M5 screw is coarse or fine... but they do mention a 4.2 mm tap drill and that is for COARSE threads: 0.80 pitch.

Chuck left the original idle screw in place and added another on the right side. Details here.

Note on taps. Most taps sold today are trash: Harbor Fright, Amazon Chinese, etc. Suspect even formerly reputable brands unless they are made in USA, UK, Germany, or Japan. These trash taps will break off or produce threads that simply do not work. You certainly don’t want any problems in a carb casting.

McMaster is a good source for taps and tap drills, among hundreds of thousands of other industrial items. McMaster stuff is seldom branded or identified by origin in the catalog, but it is all very high quality.

UPDATE. I have found I can turn the screw easily by reaching my right middle finger and my left pointer finger around the carb from opposite sides. So at this point I am not going to add another idle screw.


Adjusting the air screw

The process with an air screw is similar but a bit different from the stock carb which has a fuel screw. With the stocker, you adjust the amount of fuel. With the PWK, you adjust the amount of air. It’s just opposite ways to adjust the fuel/air mixture for low speed operation.

Process as described by the JunkMan: I extracted this flow chart from his video. * = I changed this for the CRF230F.

Download this Excel spreadsheet for your own use.  It is formatted for air screw, but fuel screw is the exact opposite. In other words, when the fuel screw is completely closed that is the leanest not richest mixture.

Process as described by Mid-Atlantic Trials

Reformatted into flow chart form from long paragraphs at

“Once running, take the bike off of choke as it begins to falter and screw in the idle screw enough to keep the engine idling.  Let the bike warm up for a couple of minutes.  

“Once warm, turn the air screw in a quarter turn and see if the engine picks up rpms.  

“Continue turning the air screw in 1/8 turns in the direction the rpms increase, until the rpms level out.  Use the idle screw during this time to keep the idle low but not in danger of stalling.  

“After each 1/8 turn, give the motor several seconds to adjust to the  new setting.  

“Once you have found the area where the engine neither increases nor decreases in rpms you are close to having the idle [air screw?] adjusted.  

“Stop the engine and check to see how many turns out the air screw is.  

“When you have reached optimum idle speed with the air screw turned out between one and two turns, you have the idle right or very close.  

“Blip the throttle slightly.  

[Symptom A] depends on the type of engine:

The process continues here for higher speed carb circuits:

It is very helpful to use a digital tach. There is a replaceable battery model with 10 RPM resolution here: Amazon. Note this uses the somewhat unusual CR2450 battery; keep a spare around.


Setting up jetting

Specs as received

Short needle jet in place and long needle jet on right:

My setup before carb swap

Other parts included with the PWK carb

Trail tests

1.0 carb as received: I went out and rode my standard test singletracks around 6500 ft. Temperature was around 60F.




Trail test at 6000 to 7000 feet

SUMMARY: This is a big project but the payoff is significant even for an uncorked bike. Attention to detail for leak-free couplings and cable routing is essential.

Above: JXG on 31, 26, 23, 17, 16, 11, 10, 9, 8, 3 December 2017

Thread on TT



Tuning the PWK for the CRF230F

Keep in mind, some CRF230F’s have been heavily modified and they are not all operated at low elevations. Always make sure you know what level of mod is being talked about and the elevation. Tuning notes by Chuck ref and more advanced ref.

BTR stock engine:

Pilot jet too rich

Pilot is OK

My current best guesses on jetting...

Elevation (feet)

Main Jet

Pilot Jet

9000 and up

110: will try

35: will try

6000 to 9000

115: good

40: good

3000 to 6000

125: will try soon

45: will try soon

1000 to 3000

135: worked for seller

40: worked for seller

Above: JXG on 16, 11, 3 December 2017



This section describes complete (or partly complete) builds to help understand how all the components work together.

Link to this section:

Frickin’ Jim Build

This extensive build is documented in a series of videos, indexed below.

Episode 1:

Episode 2:

Episode 3:

Episode 4:

Episode 5:

Episode 6:

Episode 7:

Episode 8:

Episode 9:

Note: For background information on Episodes 7-9, see Engine mods section.

Episode 10:

Episode 11:

Procom CDI and over-revving results in blown engine YouTube. See comments here.


Mixxer BunnZilla Build

Post post


Results after carb addition: “What I have right now is more grunt like a moderate big bore kit might add... And a much better run out on top... Like a bigger cam would add... Could not be more satisfied with it...” post


“Very strong runner ... No resemblance to stock power... Even with the torque biased camshaft, this setup makes very good use of the additional CFM of the larger cut carb with the choke plate removed.... Top end run-out is noticeably stronger and longer.... And that's with stock displacement...

So I'm going to bet that even a lesser mod bike would get a top end boost... [from the carb] But for certain, setups with bigger bore and stroke will really benefit from a bigger than stock carb...” post

BunnZilla Suspension 2018

“My fast 19 year old son Samuel paid an excellent compliment after running a woods track with BunnZilla and it's new suspension and more power:

"Pops, this is crazy fun, plus I'm sure I'm faster in the woods on this than I am in my 450!! Easier to ride faster!!"

(Photo courtesy of Mixxer)

Above: 27 March 2018, 27 November and 18 August 2017 by JXG with thanks to Mixxer


JXG Build

This is a backcountry bike with no internal engine mods

Full tank of gas: 126 + 135 = 261 lbs on digital bath scale

^^^ Summer config with chainsaw on front and hailstorm survival gear on back


[*] BTR Build

Post reviews these mods

Below: In high-speed desert riding, gravel bounces off the front of the engine and pits the fork stanchions. BTR wraps shields around the stanchions, made from Rubbermaid trash can plastic or thin (Schedule 140) PVC pipe. You can see a line of pop rivets that have been smashed flat.

Modified swingarm:

Quick release pins for seat:

Quick-release axles:

Axle wrench and spare shift lever:

Above: 22 February 2018 by BTR as told to JXG. Updated 16 August, 20 May 2018.


[*] Mike H. 272 Build

Thread on this build

Forks: CR85 with rebound hole plug mod (July 2018)

Shock: Fox Podium

Rebound hole plug mod (July 2018)

Results: “Mike’s new rebound mod Cr85 is a 100% fix for the too fast rebound. We agreed on 2 1/2 turns in -- so we have 1 1/2 turns more if want stiffer rebound. It now out-handles my CR85 forks. We both feel his are perfect.” BTR post 

Further reflections: “Wonder why my Susp guy and nobody else figured this out. It makes sense to me: stock springs are so weak now we have strong springs. So rebound is not able to keep up. One more Plus... remember I reported that when you turn in rebound adjuster it also makes compression damping stiffer.  So without his mod my rebound is maxed. Still too fast on rebound but at same time making comp harder witch is what I don't want.  His mod as far as we can tell has not made comp stiffer.” BTR post

PWK remote choke with tensioner from a Triumph:


Above: 4 August, 23 February 2018 by JXG with thanks to Mike H. and BTR


[*] Cop Build by BTR

Forks: XR400R, see XR400R fork swap for details

Shock: XR250R

Cop build with XR400R forks and Mike build with CR85 forks

Above: 16 August 2018 by JXG with thanks to BTR


Rocky Mountain bling build

Emphasis on bling: YouTube. This shows how few functional mods are available through retail channels.

Link to this section:


Electrical modifications

Be sure to use the corrected wiring diagram by Ramz

I like to solder connections and then seal/reinforce with a marine shrink tubing like Ancor Amazon.

HOWEVER... NASA demonstrates in classes that soldered connections fail on a vibration table and proper crimp connections do not (ref).

Here is a tutorial on crimping. Besides a good tool, it takes work and practice.

The ratcheting-is-better perspective: post

SAE trailer connectors generally work well.

I have tried Chinese Deutsch-type connectors like these Amazon. They have been reliable but are a pain to assemble. I found they had to be soldered; the crimps are too tiny to hold otherwise. You don’t need the crimping tool they suggest, just needle nose pliers and soldering. Eastern Beaver which generally advocates crimping shows how to do this here. The connector provides enough support to the wire that soldering does not cause a stress point.

Bullet connectors: link

Here are higher quality Deutsch-type connectors: link

Fusebox with screw connectors: link

Removing the key switch

Above: 31 December 2017 by JXG


Street conversion

Street conversion slide show has additional info

Trail Tech speedo battery: 1x CR2032 battery and requires 5 mm and 2.5 mm hex to remove the speedo and a quarter or large screwdriver to access the battery compartment

Here is another way to set up the rear brake switch: post


LED headlight upgrade with stock stator

Many dual-sports use a headlight shroud like the Baja Designs. Back in the day, the limited clearance between headlight and the steering head was not a problem because the traditional H4 halogen is shallow. But all these great new LEDs need more room. Here is how to get some space so you can upgrade.

The array of potential LED and HID upgrades is large and growing. Huge light at lower power draw. Frickin’ Jim has tested and reviewed many of the options:

One problem with new LEDs is they require a heat sink. Some of these are quite large and can interfere with the steering head and/or the cable bundle.

On the CRF230F, there is interference with the CDI unit, the steering head, and the bundle of throttle cable and electrical cables. Be sure to turn the handlebars from full stop to full stop as you scope out the available space.

The first option I looked at was from SuperBrightLEDs and uses copper braid as a heat sink.

The braid is flexible and can be arranged in the available space. But it still sticks out about 2 inches and interfered with the cable bundle. It’s a great concept but does not work well where there is movement.

Then there is power. The upgrades can pull many watts. I am not ready to upgrade my stator, so I looked for a lower power LED. Frickin’ Jim has figured out the power budget:

“The OEM stator is just fine for using the bike as a trail bike without lights, but if the bike is being used as a dual-sport the total draw of the lighting system will need to be kept under 40 watts, otherwise the battery WILL run dead over time with the lights on during normal riding. (reference)

This LED is only 30 watts max (2.5 amps) so it will work with the stock CRF230F stator:

VANSSI 9003 H4/H7 LED Motorcycle Headlight Kit CREE LED Light Bulb 30W 6500K White $30 on Amazon

UPDATE 23 March 2017: This unit is already unavailable and there is no obvious substitute with a compact heat sink, no fan, and low wattage.

If you just want a Daytime Running Light (DRL), this unit draws only 5 watts and has no heat sink at all:

Here is how the dimensions compare:

The mods

First I relocated the CDI unit to a spot near the coil. There is plenty of cable length.

This is a hotter location but there is really no other option. Ramz relocated his CDI years ago:

The VANSSI has a relatively shallow heat sink, but it still will not fit the BD on the CRF. So I made a pair of extender plates to move the whole BD headlight assembly forward 1 inch. I used Visio to make a template for cutting and drilling the 1 mm aluminum sheet.

Note: The Polisport Halo H4 Headlight comes with extender plates, per Frickin’ Jim. I already owned a BD so had to make my own.

The VANSSI comes with H4 and H7 adapters. The adapter is held on with a bayonet lock. The mirror should point downward: this is how H4 headlights work. The VANSSI has the three standard H4 tabs, but they don’t do anything because the BD does not have notches for them.

H4 adapter installed inside the boot. The adapter can be twisted off then reinstalled  

Unfortunately, the H4 adapter does not have a little bump that sticks up and locks it to the BD housing so it won’t rotate. However, the retaining bail seems strong enough to keep the LED from rotating.

I had to cut the boot to fit around the LED while still providing a dust seal.

Because I sometimes ride and transport in heavy dust, I ended up running a bead of silicone around the joint between the boot and LED.

Dust is also why I prefer to avoid fans on heat sinks.

Getting the boot and the bail on can be a bit of a workout. I ended up installing the bail in reverse. First the two ends, then snapping the middle connection in last.

In a low battery situation, I always want to be able to turn off the lights. So I added a booted switch visible at the left:

This upgrade has given me a reasonable headlight system without upgrading the stator.

If you want to get into accurate high/low aiming, there has been a lot of work by "Spiderman302" and others on H4 shields, spacers, etc. Here are a couple of example posts:

See Auxiliary riding lights for an alternative or addition to headlights


Above: JXG, 7 December 2016


Adding a neutral indicator LED

First of all, the CRF230F does not need a neutral indicator light. A number of riders report they have successfully found neutral without a light, sometimes more than once in a single ride. Furthermore, neutral indicator lights have a stigma associated with dual sports. Real dirt riders don’t need no indicator light because they are one with their gearbox. But, it’s a fun little project and kind of handy to have. And it can serve as a good introduction to electrical mods on the CRF230F.

Here is the starter circuit, courtesy of the Honda Service Manual (p. 17-2):

The starter circuit works as follows. The neutral switch is open except when the transmission is in neutral. (More or less: most neutral switches are approximate.) The clutch switch is open except when squeezed. When either one is closed, the bike is in a safe state and ground is completed for the starter relay. This circuit is only energized when both the starter button and ignition switch are closed.

The indicator circuit was designed by tedcool (link). It uses a diode to prevent back feed of 12v from neutral indicator lamp connection at neutral switch through the clutch switch. This allows the clutch switch to serve its original purpose while also activating the LED. The LED will only function when the ignition switch is on. If you don’t turn your ignition off, this will cause battery drain.

Components needed

Diode. A 50 volt, 6 amp rectifier diode is good. I had a 100 volt, 6 amp diode and it worked fine too. You don’t want to go much below 6 amps. (If you have a collection of 50 volt diodes, you can bundle them in parallel to sum up to 6 amps. Really? Doesn’t seem right.)

LED. Obviously there are many options for LEDs. I had a 12 mm blue bolt beam from SuperBrightLEDs. 37 lumens... is a very bright indicator. Cover with tape and now you can look at it with your remaining eye. I put a 180 ohm resistor in series and this brings it down to a nice daylight level, but it will still be bright at night. I will replace it with a green one later.

The mod

The modification is performed at two locations: back near the battery and at the front end. Here is the connection to the neutral switch with a test probe attached:

Note this is above the connector so the engine can still be disconnected easily.

A quick mockup proved out the design. Even with green tape over it the LED is very bright.

The diode and wire soldered into position. Note the line on the diode is down towards the neutral switch:

No idea why there are apparent paint marks on the wires.

The green wire has been run up and towards the front end of the bike.

The soldered area has been wrapped tightly with “X-Treme Tape TPE-XZLCLR Silicone Rubber Self Fusing Tape” (Amazon).

This is excellent tape for electrical mods because it fuses together chemically.

Neutral indicator on the dashboard:

UPDATE May 2017: I really like this indicator. When I am chainsawing on narrow trails there is a lot of workload in getting stopped and ready for action and having the light is handy.


Upgrading the start/stop switch

Back in 2014, the fourth time I rode my used, nearly-stock CRF this note resulted:

“On tight turn, I think the throttle hooked on a Juniper. Bike over-revved and went down. I was lying on right side and bike screaming because throttle now in dirt. Finally it stalled. This could have been bad. Need brush guards! Also install kill switch!”

So among many upgrades I added a “K&S Technologies 12-0101 Honda CR Style Engine Kill Switch” on the left bar. The construction is primitive but it has held up fairly well--but has been getting a bit intermittent.

Meanwhile I bought a “Sicass Racing Start/Kill Switch for 2016 KTM 300 XC-W” RMAM intending to install it on my Xtrainer but that didn’t happen.

So I decided to use it on my CRF230F. The Sicass has fancy plugs set up to match the KTM. I removed these and made the following connections:

Here is the new switch in place and the old starter switch:


In praise of horns on trail bikes

I replaced the K&S with an easy-to-hit horn button right beside the left grip.

Between the quads, sand rails, 4X4s, and rock buggies racing around blind spots I always like to be able to hit the horn fast. In fact, I am on the horn anytime I can’t see ahead a reasonable distance. Could make a small difference that makes a big difference.

Above: JXG, 30 April 2017


Electrical upgrades 2018

In 2016 I did a complete street conversion including a Baja Designs headlight. In 2017 the CRF became my primary chainsaw bike, so I installed D-Run riding lights and stuffed the wiring harness behind the chainsaw rack. I had to use the ignition switch so that the lights would not run down the battery.

This held up into December 2017 when I re-stuffed the wiring and... the bike started blowing main fuses out on the trail. Not good.

Here was the situation behind the chainsaw rack:

^^^ To help reduce abrasion I had wrapped the wiring in two pieces of inner tube. You can see one on the fender.

It was time for a revision of the wiring harness, with these goals:

I decided to use terminal strips because I like to solder connections and then seal/reinforce with a marine shrink tubing like Ancor Amazon. HOWEVER... NASA demonstrates in classes that soldered connections fail on a vibration table and proper crimp connections do not. There are NO soldered connections permitted in aviation (ref).

It will be interesting to see if this new design holds up.

Terminal strip options



Above may have quality problems

McMaster is very compact

Above: 27, 23, 17 December 2017 by JXG


New control panel with voltage meter

When I moved the chainsaw rack onto the CRF, I built a small control panel with the riding lights switch and neutral indicator LED:

I decided to build a new panel including a voltage meter.

Why a voltage meter? The CRF230F has a dirt bike electrical system: it will run without a battery. However, it won’t crank without a battery (ref). I have bump-started mine when the battery went dead (end of life), but this may not be an option on sandy flatlands, at the bottom of a rocky canyon, or on narrow singletrack.

So it is a good idea to keep an eye on the battery and charging system state of health. I decided to add a “MOTOPOWER DC 12V LED Digital Display” Amazon.

Since I wanted the panel to be very compact the first thing I did was work up a dimensional drawing in Visio:

Next I printed out the drawing on cardstock and compared it to the actual location:

Then I laid out the meter and switch boots to make sure there was enough spacing for finger operation:

The panel itself is 1 mm sheet. I used the cardstock as a template to cut out the panel with sheet metal shears. Then I center-punched the holes:

A step drill is always handy for making large holes. I usually hold the metal in my hand... the drill will bind so wear heavy leather gloves if you do this!

A piece of more flexible 0.7 mm aluminum sheet from a MC license plate wraps around the handlebar. This is pop-riveted to the panel. Two long thin machine screws tighten around the handlebar:

In my original design, the neutral indicator light was activated as soon as the ignition switch was turned on. So I added a momentary switch to power up all the accessories including the voltage meter and neutral light. I am pressing that button above.

I will add labels once the panel is fully accepted.

The panel hangs down but is fairly well protected from impact during falls. Rocks on the ground may take it out:

Above: 25, 23, 17 December 2017 by JXG



The quest for automatic lighting

The RaceTech Rec/Reg has a nice timeout function that keeps the lighting circuit on for an adjustable period after the engine stops. This Rec/Reg is expensive and will not work with a stock grounded stator.

So I decided to try to develop my own engine sensing circuit. This has turned out to not be as simple as I thought...

Back in 2014 when I had the bike only a few weeks I actually prototyped a circuit. But it would be two years until I even installed lighting. Meanwhile I owned a Beta XTrainer and loved punching a single button and having everything come to life.

The circuit (which fails!) is very simple--there are just three parts. It taps into the AC coming off the stator, converts it to DC to operate a magnet, and powers a relay to turn on a new feed line from the battery.

Based on with relay added

You can build this circuit in 30 minutes for less than $10 in parts:

Here is what it looks like:

There is no voltage regulation, so the voltage can go pretty high: 40 volts and more. But the relay only has a simple electromagnet, so I don’t think it matters much. (Just wait, the blue smoke is coming...)

I tapped into the stator AC output just under the seat, as indicated by the arrow:

^^^ The green wire and diode are for the Neutral indicator circuit

Below is the side view. A heavy (14 AWG) line comes off the battery, goes through a fuse holder, and then curves up above the airbox:

^^^ You can also see an SAE connector for a float charger. When the side panel is on, this hangs out by the shock reservoir for quick access.

Here is the layout under the seat. There is not much space for the chunky relay, so I wrapped the circuit in a plastic bag and dropped it into the airbox. It is in the corner so it does not interfere with airflow.

^^^ You can see the 14 AWG red wire coming from the left and how the blue and yellow relay lines break into it. Notice the seat rub points on the frame. All the wires under the frame. The thinner wires go to the manual override switch so the whole circuit can be bypassed if it fails.

Results. Using the Sicass switch the bike is now tap on / tap off. Very convenient!

More results.... as soon as I revved the bike high the relay burned out. Oops. That AC really is unregulated. How about that. I flipped on the bypass switch and continued with my trail ride, feeling slightly foolish. Back to the drawing board.

What is the output? "unregulated AC from 8 to 60 volts.” post

FET detector is the most elegant solution but not cheap

What about a voltage regulator as a workaround? It is difficult to find one that will handle the voltage range


Maximum Input Voltage: 40V ref

Vin – Vout difference: 3  – 40 volts ref


Power dissipation at higher voltage is going to get high ref

What about a switching regulator?

Combinations link

Input min / Input max / Output

10 / 80 / 10 but SMD package link

9 / 72 / 5 “if the input voltage changes from low voltage to high voltage abruptly, the regulator might be damaged.” link maybe add large cap  link

9 / 72 / 5 no warning like above, but again add a large cap link link $12

Calls for 3.3 uf, 100 volt on input side

5 volt relay

5 amp / 4.5 volts link

Above: 25, 23, 17 December 2017 and 9 June 2018 by JXG


Stator upgrade

Using a chainsaw rack half the year, I tend to leave it on year round and use two RUN-D LEDs for Auxiliary riding lights. This means the headlight above sits on the shelf. Problem is, these run down the battery when operated during the day for collision avoidance.

So I am going to get a stator and regulator which will provide automatic on/off also.

Above: JXG, 24 July 2018


What about brake mods?

Pros of disk brake conversion

Cons of disk brake conversion


[*] Tires

For Tubliss, UHD tubes, etc. see this page

Tire hardness data is here

What about trials tires for dry trail riding?

“A lot of people use trials tires on their 230's. The reason is that they both reward the same riding style. If you like to climb stuff with no drama, noise, or wheelspin, a trials tire on a 230 is a good choice. Both the bike and the tire type are also exceedingly durable. If your thing is sliding into corners and spinning out of them, digging ruts and throwing roost, you need a different tire (and bike).

Trials tires excel at straight line traction, especially on rocks and hardpack. They climb well. They don't destroy trails. For trail riders that primarily ride in good weather, it is the best tire. [Also in the arid west where conditions are often dry: JXG]

The weakness is loose stuff and downhills. They lock up easily on downhills and step out unexpectedly in corners. They don't work well on rocks covered thick in wet leaves, because they grip the surface instead of digging.  Mud is not as bad as you might expect, because the tread flexes and squishes the clay out of the voids. Doesn't completely pack up, but still not as good (fast) as a soft terrain tire.” post

Wet, slick conditions? VE 33 and 35 recommended post

Shinko 546 series for soft terrain post

Some people run a trials tire on the rear and MX on the front

Design of trials tires

Be aware there is always a large difference between front and rear trials tires with a similar or even identical model number.

The rears are radial, tubeless, have strong sidewalls, and last a long time. Because they are designed to put power to the ground.

The fronts are bias, tube-type, have weak sidewalls, and the sidewalls tend to wear out by flexing -- especially if you run Tubliss. Front trials tires are designed to be squishy for the rider to work with.

I have been running the IRC TR011R rear tires for a long time. Knobs are like foam rubber: Shore A = 65. Very soft, great on rock. But they last 2000 miles even so and the sidewalls never show any wear.

^^^ New IRC TR011R compared to another with 1600 miles on it. Notice fiber material of a tubeless plug in the center.

I ran one IRC TR-11 front tube-type and at the end I was plugging the sidewalls. But it did hold up for over 1500 miles. Similar experience with the D803 front. It grips very well at 8 psi with Tubliss but there is a lot of sidewall flex.

^^^ D803 front with only 30 miles on it is already showing scuffing of the sidewall

The MT43 front is not terribly hard (Shore A = 78) and the sidewalls hold up well even with Tubliss at 7 to 8 psi. “Don't worry about side knobs--not needed.” BTR post

Shinko 241 trials could not handle hard and fast desert riding. Switched to MT43. Frickin’ Jim Episode 11

Above JXG on 13 September 2018

Link to this section:



Saddlebags are a good option on the CRF230F because of their low center of gravity.

Nomadic small steel rack: 10 x 9, 3 lbs, $85;Itemid=62#!/Honda-CRF150F-230F-2003-2013-RACK-KIT/p/17623009/category=976080

Medium aluminum: $260

Large steel: 18 x 12, $200

VersaRack fork rack: $100


Carrying extra fuel

Getting more fuel out of the tank you already have post

FJim discusses the Clarke tank here

One other "Con" is having another 8 lbs (?) up high on the bike. I prefer to carry either a 2 quart Nalgene (tough) or 4 qt oil jug (not so tough) in a Wolfman saddlebag because the weight is low. But I don't like to ride over 60 miles so range is less of an issue. -JXG

Install of Clarke notes post and see BTR below it for reshaping the tank slightly

FJim is a long range guy and he discusses other options here:

I have been tempted to use an old Dromedary water bag (very tough) for gas but am now glad I didn't because I want to use it for hydration fluid.

Arizona tea jugs are OK and you can get them in a pinch -- but if you have them in a saddlebag and fall against a rock they crack.

One gallon oil jugs may be a good option.

Above: JXG on 12 April 2018


Chainsaw rigs

Material has been moved here




These are some parts that you may want to have on hand because they can be sudden show-stoppers. If you ride near home, it may not matter. I often drive several hours and spend several days in remote areas so it makes sense to have some spares along. --JXG

The basics: Complete tire repair, including tube backups for the Tubliss system.

Clutch cable can rust out or fray over time:

^^^ The bike got rained on while camping out a couple weeks before I discovered this. I suspect water went down the clutch cable and pooled up behind the rubber dust seal (not shown).

Rebuild kit: eBay

Countershaft seal can start leaking: 91216-KGH-901 OIL SEAL (20X34X7). For a buck, easy to have a spare: Partzilla

Shift shaft seal thread

Wheel bearings


1 ea. 96140-63030-10 BEARING (6303U) $9.00, RMAM $9.67         

1 ea. 96140-62030-10 BEARING (6203U)  $7.18, RMAM $11.12

1 ea. 91253-033-003 OIL SEAL (25X47X6.5) $4.21, RMAM $5.00

PZ $20.39 vs. $25.79 RMAM


2 ea. 96140-62020-10 BEARING (6202U)  $7.42, RMAM $8.82

1 ea. 91254-KA3-831 DUST SEAL (22X50X5) $6.29, RMAM $7.47

1 ea. 90755-229-003 OIL SEAL (21X37X7) $3.56, RMAM $4.24

PZ $24.69 vs. $29.35 RMAM

Battery is essential if you do trail riding where bump starting is not really an option. I had one go out when riding near home. Then I bought a spare for my AJP that also fits the CRF.

So I keep it on the BatteryMINDer Charger/Maintainer/Desulfater (Amazon) and take it along in my vehicle on extended trips. (If your battery is getting old, the load testers at auto supply stores do work on motorcycle batteries.)

Above: JXG on 15 September 2017



1.1 US Qt = 1 US Qt + 3.2 US oz



10W-30, or 10W-40 which has a temperature range that goes higher to over 100F (Owners Manual, p. 60; Service Manual, p. 3-12)

BTR email: For his modified bike, Valvoline 20W-50 MC oil synthetic. On his fleet bikes without engine mods, 20W-40 Shell Rotella diesel oil. For these bikes he changes oil after every 4 day tour.


Air filter


JXG: I have compared


Moose filters

Moose filter

Above: JXG on 25 February 2018


Spoke tightening

“Dear Mr. Know-It-All,

After reading your suggestions regarding spoke tuning on page 116 of the March 2017 issue, I just had to respond. I've worked on motorcycles for 50-plus years and have tightened quite a few spokes, especially at a Honda

dealer from 1974-1984. Customers often brought their dirt bikes in for service with wheels that had very loose spokes, as I'm sure customers still do. I currently tighten spoke nipples the same way on my 2014 KTM EXC 500 as I did on my 1974 Honda 250 Elsinore.

1. There are nine sets of four spokes on most every dirt bike I've ever worked on.

2. To begin with, if the wheel has any spoke that is severely loose (and the rim is not bent), I literally finger tighten the nipples just to snug them up. And, in general, never tighten any spoke more than one turn at a time.

3. Starting at the valve stem (or any other reference point), tighten the first set of four spokes.

-Then, skip two sets of four spokes.

-You will now be at the fourth set of spokes. Tighten, skip two sets, tighten, skip two sets, etc.

4. Eventually, you'll come around to that first set of spokes again at the valve core.

-So, move to the second set of spokes. Tighten, skip two sets, tighten, skip two sets, etc. Eventually, you will come around to the second set of spokes again.

So, move to the third set of spokes. Tighten, skip two sets, tighten,

skip two sets, etc. Doing this cycle two or three times has always worked for

me without ever causing a wheel-alignment problem.

Also, I'm generally a believer in using a torque wrench, but when it comes

to dirt bike wheel spokes, I always use sound pitch for the final torque adjustment.

The real trick here is to tighten one set of four spokes, then skip two sets, tighten, and just keep working your way around. You really should have known! Drew Richmond. Dirt Bike Magazine, November 2017.



The pull cable is the top one (I think) and runs to the front of the bike as below:

The MotionPro lubricator is expensive but it will fit over large cable ends like the top ends of the CRF throttle cable. It still leaks. Wrap a rubber glove around the opening very tightly.



BTR: “I like Honda pads best. EBC is OK also.” - post


Rear suspension inspect and grease

BTR: “We grease with boat trailer marine grease. Every bike new or used before we ride it. Also fill all cavities in center of swing arm so no place for water to park. On steering bearings we put thick line of grease above bearings in frame head. When you buy a new Honda very little grease on bearings. All the new Yamaha's we have bought have more grease than Hondas. No matter we take them apart and re-grease. If you need steering head bearings think twice about All Balls Bearings and other Mickey Mouse brands. Less than one year the bearing races have dents.” “I use OEM HONDA, they are so cheap.” - post

First up: Why you need to do it, the mineral spirits and acetone cleaning process, moly grease, grease compatibility, etc. see the AJP Shop Notebook.

Some items you need for the CRF230F:

Note swingarm can be removed without disconnecting the top of the shock. This saves removing the airbox and battery.

There is no particular disassembly sequence and the parts are unique. The washer on the rear brake shaft does block removal of the front dog bone bolt. Only the washer needs to be removed:

Linkage parts: See Reassembly section for wrench sizes. The yoke is known as the “Shock link” and triangular structure is known as the “shock arm.”

Grease seals protect the needle bearings from dirt and water:

Seal puller makes seal removal easy. Work your way around the seal at about 4 places opposite each other:

With the seal out you can now clean and regrease the needle bearings:

Linkage parts after cleaning with mineral spirits and acetone:

Linkage seals:

2 ea. #18 = DUST SEAL (20X26X4.5) (ARAI)

Part# 91254-KS6-003 (Honda Code 2159713)

Partzilla $6.29

*AVX 20x26x5 (note not 4.5, OE does not have garter spring) $1.80

6 ea. #19 = DUST SEAL (17X24X5) (ARAI)

Part# 91262-KV3-831

Partzilla $4.41

*AVX 17X24X5 (OE does not have garter spring) $1.62

* Honda is safest, but the AVX seals may work. “I think this type of duty, a grease seal which is not under pressure, can be just as easily accomplished with a cheaper seal as an OE one.  The toughest abuse most of these seals probably see is from a pressure washer.” post The description says they have a garter spring which the Honda parts do not.


2 ea. #5 = CAP, DUST SEAL (NOK)

Part #131179005772

Mfg. #52144-356-005 (Honda Code 0337915)

This is a unique Honda part that combines a washer and a grease seal. No known substitutes.

Partzilla $10.45

Results: This 2008 bike has unknown mileage, but was not ridden a lot before I got it. Since then I have put 1000 miles and 120 hours on it. I have never submerged the linkage and given the bike came from northern NM and the Durango area it is possible it has never been in water. I would guess nobody ever touched these components before.

Everything was in good shape with adequate grease in all the bearings. As you can see in the photo above, the seals were doing a good job keeping out dirt. I found one of the yoke seals had a small separation of rubber and this was replaced.

For my riding, I am thinking I will probably do this service about every 200 hours, more often if I submerge the linkage.



The linkage bolts go in this order. All should go in from the left side for better access with the torque wrench on the right side.

  1. Shock arm to swingarm: 17 mm box x 19 mm socket = 78 Nm
  1. This is the large diameter one. You may want to wait to torque it until the whole linkage is together.
  1. Shock to shock arm: 14 mm box x 17 mm socket = 44 Nm
  1. Torque this now, it will be blocked by the link
  1. Shock link to frame: 17 mm socket x 14 mm box
  1. This bolt, the longest, has to go in from the RIGHT side as shown in the Honda parts diagram above. The illustrations on Service Manual p. 13-19 and 13-20 are impossible because the left side is blocked.
  2. No torque is specified, but this bolt is the same as the 44 Nm bolts above.
  3. You can get a 17 mm 3/8-in socket in from the left side but you probably can’t fit a torque wrench. Make it tight.
  1. Shock link to shock arm:  14 mm x 18 mm socket = 44 Nm

Check that all bolts got torqued, including the 78 Nm one.

Rear axle nut is 24 mm at 108 Nm.


What about grease zerks?

“it is a crime they don't put grease fittings on them my ‘93 XR 650L has fittings and the bushings are like new 20 years later but the later year bikes they stopped installing them” - post

JXG question: Were bushings more compatible with grease fittings than needle bearings? Easier to channel the grease where it needed to go? The whole point of needle bearings is more surface area. It seems like this would produce a lot more resistance to the movement of grease under pressure.

“I have an extra Zerk fitting I bought for the swing arm. Can't remember why bought it now. Anyway, what drill bit and tap(tapered?) do I need to install a Zerk on the suspension arm?” “Can't hurt. Be sure the zerk is NPT. Some are 1/4"-28TPI. The OEM Honda zerk may be metric.”

(If you look at the assortments here, there are 6, 8, and 10 mm options. The nipple itself is standard. These seem to be straight threads, not pipe threads (NPT). So riders may have the taps on hand, while NPT is a little more rare.)

Zerks may work, but you will have to pump enough grease in there to force it into the bushings and I will bet that it will push thru the seals before getting into the bushings...ymmv”

“If the grease does not get to the sealed area of the bearings then nothing has been achieved. It is also necessary for the internal sleeve to be drilled or grooved in a manner as to allow the grease to pass thru to the bearings. A good while back a kit was sold for some bikes but they are no longer available.”

Detailed KLR installation by Wattman shows what is involved. He uses vent holes to get the grease to cross from one side of a single bearing to the other side.

“You can skip drilling vent holes entirely if you don't mind having the grease come out the seal with the least resistance.But my concern is it will come out on a side where grease didn’t cross the bearing all the way, so the vent holes make for low resistance, I always get flow where I want it, and in two vent hole locations, get flow out of each vent hole when greasing!”

If you have an uncontrollable urge to add zerks, see Installation on an AJP which is a bit similar to a CRF230F. However there is almost no space between the bearings on the CRF. I’m really not sure there is sufficient space for grease flow in these compact assemblies.

Above: 11, 3 January 2017 by JXG


2017 linkage service

I had planned to go to 200 hours, but the rear suspension started squeaking in a long descent in heavy rocks. It was 91 hours and about 900 miles since I greased the bearings. Total mileage and hours unknown.

Once I got the bike up on the lift I discovered there was a pine cone jammed into the linkage area. Pine cones have rosin. Rosin squeaks. I removed the pine cone with great difficulty and bounced the rear end. Still squeaking.

Then I decided to pressure wash the bike, taking the usual care to avoid blasting water into bearings. It stopped squeaking, possibly because the gravel between the swingarm and rear case was gone. But I decided to go ahead and service the suspension.

Everything looked good. No dirt or water had gotten past the seals and the grease still looked good. But there was some seal damage:

Triangle or “shock arm” consists of 3 bearing sets:

1. Long, the dog bone connector and most exposed: big chip out of lip:

2. Short small diameter, the shock eye: dimple in lip:

3. Short large, the swingarm connection: slightly bent lip

Dog bones front, most protected: No lip damage

I decided to purchase a complete set of Honda seals and replace them all. My interval is 200 hrs, let’s see if I make it this time. Next time I will try AVX seals as listed above.

Above: 12 September 2017 by JXG


Steering stem how-to

BTR: “If you need steering head bearings think twice about All Balls Bearings and other Mickey Mouse brands. Less than one year the bearing races have dents.” “I use OEM HONDA, they are so cheap.” “On steering bearings we put thick line of grease above bearings in frame head.” - post

Deluxe approach:

Budget approach:

* If you get a socket instead, then torque can be set exactly. Also the steering stem nut takes a lot of torque and it is hard to do this with the box wrench.

Delboy is a skilled bloke. If you like to buy tools, buy the tools. I did the budget method for my CRF150RB fork swap and it works. You just have to be patient and take your time. Before removing the races, study and maybe measure how deep they are in the frame. If a new race starts going crooked, don’t panic. Tap more on the opposite side and it should straighten out. If it doesn’t, tap it out carefully and try again.

The bottom race is challenging. It’s a lot of hammering in an awkward position. I will try 1/2-inch all-thread next time as a homemade driver to pull the race into position.

Above: 28 June 2017 by JXG


Cam chain tensioner: Replace with Tokyo Mods?

The coiled “watch spring” ends can break off:



Woodsryder has an interesting opinion



BTR: “Do NOT USE EBC CLUTCH or CLUTCH SPRINGS, pure junk.” - post


Fork Seals

This may be an alternative if there is dirt in the seals

The key is to carefully study and follow the shop manual. A couple photos:

Prying the dust seal off. The oil seal with its retaining clip is underneath this:

The Tusk adjustable seal driver is reasonably priced and well worth it:

Above: JXG on 30 April 2017


What about Seal Savers?

Replacing fork seals is a lot of work and not cheap either. Seal Savers are a good investment.

Zip-On’s can be installed in a matter of minutes and do not require removing your forks from the triple clamps.”

“They make standard fork boots completely obsolete”

The zippers are not the highest quality. Spraying on some Teflon lubricant can help.

As you can see, dust and dirt builds up so it is a good idea to wash them regularly:

^ Those streaks at the top are rubbing the fork stanchions.

Above: 19 January 2018, 10 June 2017 by JXG


Chain guide

Post on breaking chain guide while riding in rocks. The front mounting hole broke completely after a while: 

Other than that, the guide was in good shape so I did not want to buy a new OEM at close to $30 Partzilla and the Outlaw is reportedly junk post.

So I just took some aluminum sheet from an old project box and pop-riveted it into place:

UPDATE: BTR points out it is better for the aluminum sheet to extend over the whole guide.

Above: 25, 16 December, 4 September 2017 by JXG



Reinstalling the tank and seat

The CRF230F seat is not exactly quick release. I reinstall mine just infrequently enough that I forget the little tricks. So I am going to write them down:

  1. Slide on the tank, lining up the front mounting bolts
  2. Install the front bolts loosely
  3. Attach the rear bungie that holds down the tank
  4. Slide the seat into the front connection while also making sure the middle tab goes under the metal loop and the rear tab goes into the rear slot: this is important!
  5. Install the left and right rear seat bolts: 12 mm socket, collar, and 12 mm box wrench on the nut. Make sure they are tight.
  6. Install left side panel....
  7. Align the battery retaining strap and install the short 10 mm bolt at the bottom
  8. Install the long 10 mm bolt at the top
  9. Install the hex screw at lower rear
  10. Install right side panel
  11. Install the hex screw at lower rear
  12. Tighten the front bolts

Above: 1 December 2017 by JXG


Fuel and Storage

High octane? “As far as octane requirements, any pump gas will be just fine... The stock 230 is supremely low octane tolerant with it's low cylinder fill and low compression.... Bulletproof...” Mixxer post

BTR with his high compression engine and high temperatures always runs premium. He also runs premium in his stock engine CRF230Fs.

Don’t drain fuel for storage

Above: 5 September 2017 and 15 Feb 2018 by JXG


How to be notified of updates to this document

To be notified when there is an update, you can create an alert at Choose “When a specific element changes” and point it at the date at the top of the page. You will get an email when this date changes. does not seem to work with Google Doc web pages.


Tables for photos







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