– 30 –
3. TROUBLESHOOTING
If the engine shows any sign of malfunction, the cause should be determined immediately and
appropriate countermeasures should be taken to prevent the problem from worsening. This section
describes certain known problems, their possible causes and appropriate countermeasures. Note,
however, that the list of problems presented here is not all. Generally speaking, since there is the
possibility of multiple causes for a single problem, please use your experience and common sense
when deciding on what action to take.
8) Insufficient tightening of spark plug
Retighten
Problem and possible cause
Starting difficulties
Remedy
1. Ignition system problems
3) Improper air gap between ignition coil and flywheel
1) Spark plug
• Improper spark plug gap
• Insulation defect
• Carbon deposits
2) Ignition coil
• Insulation defect or discontinuity
• Poor contact or broken wire
Adjust the gap
Replace
Clean
Replace
Repair or replace
Adjust
2. Fuel system problems
5) Carburetor
• Overflow
• Clogged or damaged
• Throttle valve malfunction
(does not close fully)
1) No fuel in fuel tank
2) Fuel hose clogged or pinched
3) Air in fuel lines
4) Poor quality gasoline or water in gasoline
Adjust
Overhaul
Check and adjust
Replace
Refill
Clean or replace
Check and retighten joints
3. Engine core components
problems
1) Insufficient tightening of cylinder head bolts
2) Wearing of piston, piston rings and/or cylinder
3) Improper contact of valve and seat
4) Valve sticking
5) Improper valve clearance
6) Leakage from intake manifold gasket
7) Leakage from carburetor gasket
Check and retighten
Repair or replace
Repair
Repair
Adjust
Retighten; replace gasket
Retighten; replace gasket
