Engine crank
train
mechanism
Engine unable to start or
engine cut-
off while travelling:
1. When condition of
carburettor & spark
plugs are normal but
compression
pressure is abnormal
1. Damaged or worn-out piston
ring
2. Stucked / unmovable piston
ring
3. Air leakage of intake valve
4. Air leakage of cylinder head
5. Starter spring is broken
6. Worn-out starter gear
1. Replace damaged or worn-out piston ring
2. Clean the piston and ring
3. Adjust or replace intake valve
4. Replace the cylinder gasket head
5. Replace starter spring
6. Replace starter gear
2. Abnormal operation of
engine, traces
of knocking sound are heard
1. Damaged or worn-out
piston, piston ring or cylinder
2. Damaged or worn-out piston
pinhole
3. Worn-out crankshaft ball
bearing
4. Worn-out connecting rod
needle bearing
5. Huge gap/clearance
between intake & exhaust
valve
6. Worn-out camshaft, cam
axle sleeve, rocker arm &
rocker arm axle sleeve
7. Oil leakage in engine
operation components
1. Replace piston & piston ring boring block
2. Replace piston pin and piston
3. Replace crankshaft ball bearing
4. Replace connecting rod needle bearing
5. Adjust gap/clearance between the valves
6. Replace camshaft, cam axle sleeve, rocker arm
& rocker arm axle sleeve
7. Add or top-up engine oil
3. Spark plugs are normal but
engine
operation is abnormal
1. Traces of water in the fuel
1. Clean the fuel supply system and related
components
4. Insufficient temporary
horsepower
1. Faulty or worn-out spark
plugs
2. Overheated engine
1. Replace faulty or worn-out spark plugs
2. Cool overheated engine and avoid long periods
of driving
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