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I
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and the swingarm. The radiator overflow tube runs down the front left frame rail.
Make sure the transmission vent line is properly secured and pointing to the rear of
the bike so it does not tend to gather water. If the line is removed from the vent fit-
ting, make sure to always replace it. Make sure the gas cap overflow hose is not
kinked, twisted or clogged. Any obstruction can cause the tank to develop a vacuum,
which will prevent gas flow to carburetor. See section II-4 for proper hose routing.
15. Reed valve, intake boots
Check rubber intake boots to make sure clamps are on in the proper location and
are tight. Any leak will suck in dust and quickly destroy the motor. A leak between
the carburetor and case will cause the motor to run lean, which will cause the idle to
climb and could cause piston damage under heavy load. Check boots for cracks or
punctures. The engine uses a reed block assembly to run properly. If the reeds are
damaged, frayed or worn, the motor will have low compression and will be hard to
start and down on power. If a reed breaks it will be sucked into the piston which can
cause considerable damage. Check reeds whenever the engine is serviced, and replace
reeds if they don’t sit flat against sealing surface or if they show any visible wear at all. Use blue threadlocker on 4 screws securing
reeds during reassembly. Install reed valve to case using a new gasket and torque 4
Xmm
allen bolts to
XX ft/lbs
.
16.1 Engine Service - rings & piston
Under racing conditions, ring replacement is recommended every 10 hours of use, and piston replacement after every 20 hours of
use. For practice and occasional race use, replace rings every 20 hours and piston every 30 hours or if power seems less than usual,
the motor “pings” or becomes hard to start. Timely ring replacement will extend the useful life of the piston. Any excess ring wear
will immediately and dramatically reduce top end power and will make starting more difficult. Always use new rings & circlips (2)
when replacing piston, replacing rod bearing and pin with each new piston is also a good idea. Use of a high quality synthetic or
semi-synthetic premix oil such as Maxima K2 will greatly extend piston life and reduce spark plug and muffler fouling.
Piston & ring removal
Clean motorcycle thoroughly to prevent dirt from falling into motor.
Remove seat
- Remove screw at rear of seat using a large flat screwdriver,
then pull seat rearward and up.
Remove fuel tank
- Remove fuel tank mounting screw using a large phillips
screwdriver. Pull end of vent hose out of gas cap. Make sure fuel valve is off,
then pull rubber hose off fuel valve. Pull tank off motorcycle and set aside
away from fire or sparks, taking care that fuel does not spill. Make sure to
cover end of fuel valve, or prop off ground to prevent dirt from entering it. Do
not lose two rubber insulators under gas tank.
Remove expansion pipe
- Remove spring(s) attaching pipe to cylinder. A tool
can be purchased from your local dealer or Action Racing which will ease this
task. (See photos III-9 and III-10)
Remove lock nut from rubber pipe mount (located on right frame rail near
exhaust springs) Gently twist pipe side to side and pull forwards to detach it
from cylinder exhaust extension. When pipe is free of cylinder, turn front
wheel to right, then continue to pull rear of pipe out of muffler. When pipe is
free, pull it forward, and then rotate top of pipe outward (see photo III-11) and
carefully guide pipe out of frame rails. Do not force pipe.
Remove exhaust extension by removing two socket head screws using a
5mm allen wrench. See photo III-12.
Drain coolan
t - Make sure bike is cool. Loosen radiator cap. Put a container
under bike to collect coolant. Remove socket head drain bolt (see illustration III-
13, III-15) using 4mm allen wrench and allow coolant to drain. Remove cap and
lean bike to help insure complete draining. Make sure copper sealing washer is
on bolt, then re-install bolt
snugly
to prevent loss.
Reed valve assembly.
III
III
.8
.8
Remove 2 springs, and nut from exhaust mount.
III
III
.9
.9
Homemade spring removal tool.
III
III
.10
.10
