Tools Description

10 mm socket / wrench

17 mm socket / hex key 

extension bars

Torque wrench 

Tray to hold removed parts

Measuring cup

Small ruler

Small syringe / tube  

Oil pan 

Oil Height tool

Latex gloves ( I always wear them when working with oils/chemicals )

Eye Protection ( Good security, just in case )

Paper towels / rags to clean parts

Qty

Parts / Supplies

1

1

1

Motul 15W Fork Oil or equivalent

Price: $10.00 

 Odorless Mineral Spirits (cheaper by the gallon)

Price: $10.00 

Dexron ATF (Transmission Fluid)

 Price: $4.00 

Time

 Difficulty

Service Interval

60-90 Minutes

 Medium

 As often as needed 

Preliminary Steps

• Remove the  Handlebar Covers
• Remove the  Front Panel
• Remove the  Front Wheel Removal--Install
• Remove the   Front Fender
• Remove the Calipers Left / Right  Front Brake Pads Maintenance

Fork Oil Change Steps

• Loosen the front fork upper clamp bolt

        Note: Slightly loosen the front fork cap bolt before loosening the lower clamp bolts to facilitate later

                 disassembly.

• Loosen the front fork lower clamp bolts.

        Note: Hold the front fork by hand to prevent it from sliding out of the steering stem.

• Remove the front fork cap bolt with a 17 mm  hex key / socket

• Remove the spacer, washer and spring

• Invert the fork and drain the fork oil out of the fork by stroking

• Hold the fork inverted for a few minutes to drain the oil.

Complete Fork Disassembly Steps

This section is provided as a courtesy just in case you need to take the fork apart.

• Remove the cylinder bolt

        Note: If the cylinder turns together with the cylinder bolt, temporarily install the fork spring, spacer, washer

                 and cap bolt to prevent the cylinder from turning.

• Remove the cylinder and rebound spring.
• Remove the dust seal.
• Remove the oil seal stopper ring.
• Pull the inner tube out of the outer tube.

        Note: Be careful not to damage the inner tube

                 Caution: The slide metal, guide metal, oil seal and dust seal must be replaced with new ones when

                 reassembling the front fork

• Remove the following parts

• oils seal
• oil seal retainer
• guide metal
• slide metal
• oil lock piece 

Below is a picture of a fork taken apart, provided by MJR on BUSA:

Fork oil replacement

• Place the front fork vertically without the spring.
• Compress the front fork fully.
• Pour the specified front fork oil into the front fork

        99000-99044-10G: Suzuki fork oil #10

        Front fork oil capacity (each leg): 482 ml (16.29/16.97 US/Imp OZ)

• Move the inner tube up and down several times until no more bubbles come out from the oil.

• Keep the front fork vertically and leave it for 5-6 minutes

        Note: Take extreme attention to pump out air completely.

• Hold the front fork vertically and adjust the fork oil level with the special tool:

        Note: When adjusting the fork oil level, remove the fork spring and compress the inner tube fully.

       Tool:  09943-74111: Front fork oil level gauge

       Data: Fork oil level: 129mm (5.08 in)

       Oil:    99000-9044-10G: Suzuki fork oil #10

Fork Springs

• Install the fork spring into the front fork
• Install the washer and the spacer

        Note: The smaller spring pitch end must face upward.  (take note when removing the springs in the first place)

Fork Cap Bolt

• Apply fork oil lightly to the O-ring.

        Caution: use a new o-ring to prevent oil leakage.

• Tighten the front fork cap bolt temporarily.

• Set the front fork to the front fork lower bracket temporarily by tightening the lower clamp bolts.

• Tighten the front fork cap bolt to the specified torque with the special tool.

        Tool: 09940-30230: Socket Hexagon (17 mm)

        Torque: Front fork cap bolt: 23 N-m(2.3 kgf-m, 16.5 lb-ft)

• Align the top of the inner tube with the upper surface of the steering stem upper bracket.

• Tighten the front fork upper and lower clamp bolts.

        Torque: Front fork upper clamp bolt: 23 N-m(2.3 kgf-m, 16.5 lb-ft)

                         Front fork lower clamp bolt: 23 N-m(2.3 kgf-m, 16.5 lb-ft)

• Install the front fender
• Install the front wheel and brake calipers.

        Note: After installing the brake calipers, front brake should be efficient by pumping the front brake lever.

Preliminary Steps

You must remove some parts to gain access to the front forks. 

I will not be covering them in detail here as each task has its own individual DIY which you can consult to familiarize yourself with the necessary steps.

The removal / installation steps below apply equally to either fork, Left or Right, and can be performed in any order.

I would recommend that you do one fork at a time from start to finish.

Below are a few pics of what you should be looking at before removing the forks:

DIY - Fork Oil Maintenance

 Step 

Removal Steps

1.

Loosen the front fork upper clamp bolt using a 10mm socket / wrench.

Tools:  

• Using a 10 mm socket, loosen the upper clamp bolt
• Don’t remove the bolt

2.

Slightly loosen the front fork cap bolt using a 17mm socket / key before loosening the lower clamp bolts.

This will greatly help later on when you remove the cap entirely. 

• Measure the cap clearance at the top of the upper clamp.
• Mine were the same on both sides, 5 mm
• This will help when you reinstall the forks

• Loosen the cap bolt using a 17 mm socket / hex key
• It doesn’t take a lot of force, its only torqued at 16.5 lb-ft
• A few turn should be enough
• I had to use an extension bar because the handlebars were in the way

Note:  Be careful as the cap is under pressure and you don't want it too loose, loosen it just enough so you

          don't have to fight with it later on.

3.

Loosen the front fork lower clamp bolts using a 10mm socket / wrench.

Tools:  

• Loosen the lower fork clamp bolts, one at a time
• Get a feel as to how loose they need to be so the fork won’t fall / slide out on its own

Note:  Hang on to the fork as it could slide out of the steering stem assemblies after the lower bolts are undone.

4.

Remove the fork from the steering stem assemblies, upper and lower.

• Reach in and grab the fork slider tube with both hands and pull out the fork
• You may have to twist and turn the slider tube to free it, mine need it.

• You need about 3 inches of additional clearance at the front to pull the fork out.
• Be careful not to drop the fork, it is kind of heavy.
• Set the fork aside once removed.

• You should have a clear view of the triple tree once the fork is removed.

5.

Secure the removed fork leg inside your work table/vise.

Tip:   Put a towel around the fork to protect it from getting scratched.

Note:  Take extra precautions to not scratch the polished surfaces of the fork tubes as they can damage the

          fork seals and lead to oil leaks.

6.

Remove the fork cap bolt entirely using a 17mm socket / key.  

• Insert the 17 mm socket into the fork cap bolt and start to unscrew it.
• Place your hand over the cap bolt and hold on to it as you loosen it.
• Remember the cap bolt is under pressure and will fly off if not held in place.
• Try to sense the pressure level as the cap comes loose by holding on to it.

Note:  The cap part is made out of aluminum and is somewhat sharp on the edges, be careful no to cut

7.

Remove the long metal spacer inside after removing the cap.

• Once the cap bolt is removed the metal spacer will pop up.
• Reach in and remove it.
• Place a paper towel under to catch any oil drops.

8.

Remove the Washer

• I use a small magnet tool with a telescopic arm to fish out the spacer.
• Place the magnet inside the fork and take out the spacer.
• Place a towel under it to catch any oil drips.

9.

Remove the Spring

• Reach in with the magnet tool and extract the fork spring.
• Pay attention to its orientation, the small wound part faces up.
• Put a towel under the spring to catch the oil drips.

Here is a picture of what the removed parts look like:

Note:  You can also just invert the fork and let all the spacer, washer and spring fall out.

          I prefer to extract them one by one verticall so I don’t hve to fish them out of the fork oil tub.

10.

At this point go to your oil collection pan and turn the fork upside down.

• Empty the fork oil into the collection pan.
• Pump the fork a few times to force any trapped oil out.
• Repeat the pumping until the oil flow stops or comes to a trickle.

11.

Invert the fork and hand it upside down

• I hung the fork upside down from my bicycle work stand using two bungee cords
• I left it for 5 minutes.
• I stroke the fork a few more times to cycle any trapped oil out
• I repeated the above for two more cycles.

At this point you are done with the fork removal steps.

You can repeat steps 1-11 for the other fork once you have reassembled and reinstalled the one you are working on.

  Cleaning

Clean the removed parts, Spring, Spacer and Washer, they are probably covered with some gunk.

• I first used some paper towels to remove the gunk build up.
• I followed with 50 %rubbing alcohol to remove any oil and leftover residue.

• Clean the fork’s lower.
• Clean and polish the slider tube surface with a soft piece of cotton cloth.
• Be careful to not scratch the surface of the slider tube.
• Clean the inside of the triple tree clamps, the upper and lower clamps.

Inspection

Inspect the following:

• Check the slider tube for any imperfections, especially at the bottom where it enters the fork.
• Check the dust cover for cracks or imperfections.
• Check the fork legs for any signs of wear or structural wear and tear.

Replace any parts that may need it.

• Measure the service limit of the fork springs (minimum is 341 mm)

Flush

At this point you have to decide on whether you simply want to add some fresh oil to the fork and be done with it or perform a few extra steps to remove any gunk build-up inside the forks.

Skip the flush section and go to the Reinstallation section to complete the fork oil change task.

Gunk and grime can build-up over time and reduce the optimum operation of the fork's internal parts over time. 

Flushing the fork can remove the majority of those foreign elements. 

Flushing the forks consists of adding some fluid back to the fork, cycling it a few times and then pumping the added fluid out.

The operation should be done as many times as necessary until the liquid coming out is clear and shows no signs of foreign elements.

There a number of different products that you could use to flush the forks, this is what I used:

I perform 3 additional interim flushes before adding new fork oil.

Step

Installation Steps

The reassembly process consists of the following:

1. Measure and add the recommended amount of fork oil (482 ml)
2. Measure the fork oil level height (129 mm)
3. Add the removed parts, spring, washer and spacer
4. Add a new o-ring to the cap bolt and install it
5. Place the fork inside the triple tree
6. Torque the cap bolt, lower and upper fork bolts

1.

Place the fork side-up vertically and secure it in place.

• Place the fork in work bench and secure it in place
• Check its level

2.

Compress the fork fully by pushing the inner tube all the way down without the spring.

• Push the slider tube all the way down until it bottoms out

3.

Measure and pour the specified fork oil quantity into the fork.

• Measure and add the recommended amount of fork boil

Front fork oil capacity (each leg): 482 ml (16.29/16.97 US/Imp OZ)

4.

Cycle the inner tube up and down several times until no more air bubbles come to the surface.

It is important to get all the air bubbles out of the fork.

• Keep the fork level
• Cycle the inner tube as many times as it takes to get all the air bubles out
• No air bubbles should come to the surface when you cycle the tube
• Use a flash light to look inside the fork
• Let the fork sit for 5-10 minutes

5.

Check the fork oil level / height.

• Using the special tool, check the fork oil level height which should be 129 mm (5.08 in)
• Make any necessary adjustments, remove / add oil until you get the right height
• Place the tool over the level fork tube
• Check dip tube to make sure it was submerged in oil, if not add oil
• Suck out any additional oil if necessary

Fork Oil Level:  129 mm (5.08 in)

6.

Insert the fork spring back into the fork by letting it slide in.

• Compress the fork fully
• Place the fork spring back into the fork
• Make sure that the smaller pitch, smaller wound circles face upwards.
• Let the spring sink into the fork with the fresh oil

Note:  The smaller spring pitch end must face upward. 

7.

Insert the washer.

• Drop the washer over the fork spring
• Make sure it remains horizontal

8.

Insert the spacer. 

• Install the spacer
• Drop the spacer in over the washer
• Some of it will stick out with the fork compressed

8.a

If you are adding any additional spacers, place them on top of the spacer before putting the fork cap back on.

This would mean that you will have to exert more force when pushing down on the spring to re-install the fork cap.

9.

Install the fork cap by doing the following:

• Replace the O-ring on the cap with a new one.
• Apply a thin film of fork oil to the O-ring.

• Pay special attention to the threading inside the fork tube

• Raise the fork to its heighest level
• Place the cap over the fork spacer
• Make sure you have a good seated position
• Push down on the cap while holding the fork tube and twisting and turning the cap
• Hand tighten the cap until the O-Ring is fully seated 

Note:  Be careful not to damage the threads on the fork and the fork cap.

10.

Reinstall the fork back on the scoot.

• Insert the for back into the triple tree from the bottom
• Line up the top of the fork steering tube wih the top of the top clamp
• Temporarily tighten the lower fork bolts

11.

Torque the fork cap to the specified spec using a 17mm hex socket / key.

Tools:  

• Set your torque wrench to the specified torque level

Front Fork Cap Bolt: 23 N-m(2.3 kgf-m, 16.5 lb-ft)

• Torque the fork cap bolt

12.

Double check your fork cap alignment.

• Make sure the top of the inner tube lines up with the upper surface of the steering stem upper bracket.

13.

Tighten the upper and lower clamp bolts to the following specs:

• Torque the lower clamp bolts to the specified torque
• Torque the upper clamp bolt to the specified torque

Upper clamp bolt: 23 N-m(2.3 kgf-m, 16.5 lb-ft)

Lower clamp bolt: 23 N-m(2.3 kgf-m, 16.5 lb-ft)

Almost Done

You are all done with one fork leg, now repeat the steps above for the other fork and you will done with the fork oil maintenance project.

Once you have serviced and reinstalled both forks, take a moment and double check your line up.

• Take the front wheel axle and thread it through the forks from left to right
• Thread it all the way, hopefully everything will line up.
• If the axle doesn’t thread correctly, take it out and double the height alignment for both forks.

Install the front fender.

Install the front wheel and brake calipers.

Lower the scooter.

Put the scooter on the center stand.

 Final Check / Testing

It's time for a final check. 

• Straddle the scooter and take it off the center stand. 
• Push down on the forks to check play and rebound.
• Double check around the seals to make sure that there are not oil leaks.
• Take the scooter out for a test drive, be careful for the first few miles. 

Keep an eye on the forks for the first few days for any signs of oil leaks, hopefully everything will work better than before.