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Top End

By: Zay, Anlon, David

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How it was at first-Disassembly

  • Head:
    • Good condition with intact fins, however we did think that the valves were bent originally
    • Spun up the valve on the lathe and cleaned it to make sure it was straight
    • Lots of carbon buildup on valves and exhaust
    • Good gasket surfaces with few scratches
    • Valve removal tool
  • Barrel:
    • A few small and shallow scratches but otherwise good
    • Was already bored out to be 20 thousandths over
    • Some corrosion on the outside but good gasket surfaces
    • Had ring that extended beyond gasket surface that extended into head
      • Better sealing
  • Piston:
    • The pin was a little worn and as such was hard to remove
    • Piston itself was larger than original and also had marring on the sidewall

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Original Pictures

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What we did-Head

  • Head
    • Sandblasting
      • Focused on getting rid of carbon in exhaust port
      • Avoided sensitive and machined areas
        • Taped off gasket surface and used old valves
        • Put on old valve covers
    • Restoration
      • Lapped gasket mating surface with 600 grit sandpaper and a flat worktop
      • Lapped the valves with lapping compound
        • Used coarse grit and then fine grit
        • Used suction cup to twist the valves
        • Bluing liquid for checking mating surface
      • Polished valve covers with buffing wheel and compound and then sealed it with the mag polish
  • Barrel
    • Sandblasting
      • Focused on getting rid of corrosion
      • Taped off important surfaces and stuffed shop towels inside the cylinder
      • Painted the outside with high temperature black paint
    • Honed inside of barrel

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Progress Pictures

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Hiccups

Mostly in reassembly:

  • Rubber gasket thickness and pushrod made the head not fully go on at first (had to use liquid gasket)
  • Paper gaskets not precisely the right size
  • Setting the timing of the spark to top dead center
  • Piston rings are 120º offset, and they expand under pressure of engine

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Reassembly Pictures

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Reassembly Pictures

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Reassembly Pictures Continued

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Final product

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meanwhile:

Green Motorcycle

  • Electrical
  • Exhaust
  • EFI

Red Motorcycle

  • Electrical
  • Clutch Cable
  • Oil Drip
  • Carb

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Thank you!