Generic Race 50, Service Manual

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Trouble diagnosis program for engine power lack
Engine power lacks
Erect main jiffy stand to enable wheels to be lifted
off ground and then rotate them by hand
Wheels rotate
freely
Wheels rotate
dully
Check tire
pressure
1. Check brake for retard
2. Check wheel bearing for
excessive wear or damage
3. Check for missing or
comparatively short intermediate
spacer of wheel hub
Air pressure
too low
Air pressure
normal
Check tire valve core for air
leak and check for pierced
or cracked tire
Remove spark plug, block its threaded
hole by finger, and then depress start
button or rapidly depress starting lever.
Fingers feel that gas dashes out
making “pow…pow” sounds
Fingers do not feel that gas dashes out
Compression pressure of
cylinder normal
Compression pressure of
cylinder insufficient
1. Check all joints outside
engine for air leak
2. Check for the piston ring
broken or locked in groove or
having insufficient elastic
force
3. Check piston ring and
cylinder for wear
Start engine, increase throttle opening
slowly and observe for speed change of
engine
Engine speed rises with increase of
throttle opening
Engine speed can not rise with increase
of throttle opening
Use an ignition timing light to
detect if engine ignition
timing is correct
1. Check for clutch slip
2. Check drive belt for excessive wear
3. Check centrifugal rollers on head
pulley for excessive wear
4. Check cones on driving wheels and
moving friction wheels for excessive
wear or grooves caused by wear
5. Check cones on driven wheels and
moving driven wheels for excessive
wear or grooves caused by wear
6. Check raceway on inner end face of
moving friction wheel for excessive
wear or pits caused by extrusion
1. Check fuel supply system for
unobstructed fuel supply
2. Check carburetor, air cleaner and
exhaust muffler for clogging
3. Check vacuum diaphragm on
plunger valve of carburetor for map
cracking or breakage
4. Check carburetor float for
improper height
1. Check CDI igniter
for malfunction
2. Check magneto
flywheel and trigger
coil for looseness