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Symptom: Engine lacks power
Air pressure too low
Check if valve core leaks
or tyre is broken.
Finger can feel strong air blasting out
and meantime make a pitpat sound
Compression pressure in the cylinder is normal.
Start engine and accelerate gradually and
observe variation of engine RPM.
Engine RPM rises as accelerator enlarges
1. Check if clutch slips; 2. Check if
transmission belt is excessively worn; 3.
Check if the centrifugal roller of driving wheel
is excessively worn; 4. Check if conical
surfaces of driving wheel and mobile friction
wheel is excessively worn or worn to groove;
5. Check if conical surface of driven wheel
and mobile driven wheel are excessively worn
or worn to groove; 6. Check if raceway on the
inner end face of friction wheel is excessively
worn or pitted due to crush.
Diagnosis procedures
Lift it with main stand to have the wheels off the ground. Rotate wheels by hands.
Wheels rotate freely.
Check tire pressure
Remove spark plug and block the screw hole of spark plug with a
finger. Press starter button or kick starter pedal.
Engine RPM does not increase as accelerator enlarges
Use an ignition timing lamp to check
ignition timing of engine
1. Check if fuel supply system is smooth;
2. Check if carburetor, air cleaner and
exhaust muffler are clogged; 3. Check if
vacuum diaphragm of plunger valve on
carburetor is cracked or broken; 4. Check
if height of carburetor float is proper.
Engine lacks power
Air pressure normal
Compression pressure in the cylinder is not enough.
Yes
Wheels rotate inflexibly.
1. Check braking drag; 2. Check if
bearing of wheels are over worn or
injured; 3. Check if the middle spacers
in the hub are missed or short.
Finger cannot feel strong air blasting out.
1. Check leakage at external
connection
parts
2.Check valve timing; 3. Check if
valve clearance is too small; 4.
Check tightness between valve
and valve seat; 5.Check if piston
ring is broken or stuck inside the
ring groove or of less elasticity; 6.
Check wear and tear of piston
ring and cylinder.
No
1.
Check
igniter. 2. Check if
magneto flywheel
or
trigger
looses.
of
engine;
CDI
coil
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