SERVICING INFORMATION 7-2
Engine runs
poorly in high-
speed range.
Dirty or heavy
exhaust smoke.
Engine lacks
power.
Engine overheats.
1. Excessively worn cylinder or piston rings.
2. Stiff piston ring in place.
3. Spark plug gaps to narrow.
4. Ignition not advanced sufficiently due to poorly working CDI
& Ignition coil unit.
5. Defective magneto stator coil.
6. Float-chamber fuel level too low.
7. Clogged air cleaner element.
8. Clogged fuel hose, resulting in inadequate fuel supply to carburetor.
9. Clogged fuel cock vacuum pipe.
1. Too much engine oil to the engine.
2. Use of incorrect engine oil.
1. Excessively worn cylinder or piston rings.
2. Stiff piston ring in place.
3. Gas leaks from crankshaft oil seal.
4. Spark plug gaps incorrect.
5. Clogged jets in carburetor.
6. Float-chamber fuel level out of adjustment.
7. Clogged air cleaner element.
8. Fouled spark plug.
9. Sucking air from intake pipe.
10. Slipping or worn V-belt.
11. Damaged/worn rollers in the movable drive face.
12. Weakened movable driven face spring.
13. Too rich fuel/air mixture due to defective starter system.
1. Heavy carbon deposit on piston crown.
2. Defective oil pump or clogged oil circuit.
3. Fuel level too low in float chamber.
4. Air leakage from intake pipe.
5. Use of incorrect engine oil.
6. Use of improper spark plug.
7. Clogged exhaust pipe/muffler.
Replace.
Replace.
Adjust.
Replace.
Replace.
Adjust or replace.
Clean
Clean, and replace.
Clean.
Check oil pump.
Change.
Replace.
Replace.
Replace.
Adjust or replace.
Clean.
Adjust or replace.
Clean.
Clean or replace.
Retighten or replace.
Replace.
Replace.
Replace.
Replace.
Clean.
Replace or clean.
Adjust or replace.
Retighten or replace.
Change.
Change.
Clean or replace.
Trouble with
starting.
Idling or low-speed
trouble.
Medium or high-
speed trouble.
Overflow and fuel
level fluctuations.
1. Starter jet is clogged.
2. Air leaking from a joint between starter body and carburetor.
3. Air leaking from carburetor’s joint or vacuum hose joint.
4. Starter plunger is not operating properly.
1. Pilot jet, pilot air jet are clogged or loose.
2. Air leaking from carburetor’s joint, vacuum pipe joint, or starter.
3. Pilot outlet is clogged.
4. Starter plunger is not fully closed.
1. Main jet or main air jet is clogged.
2. Needle jet is clogged.
3. Fuel level is improperly set.
4. Throttle valve is not operating properly.
5. Fuel filter is clogged.
1. Needle valve is worn or damaged.
2. Spring in deedle valve is broken.
3. Float is not working properly.
4. Foreign matter has adhered to needle valve.
5. Fuel level is too high or low.
Clean.
Check starter body and carburetor
for tightness, and replace gasket.
Check and replace.
Check and replace.
Check and clean.
Clean and replace.
Check and clean.
Check and replace.
Check and clean.
Check and clean.
Check and replace.
Check throttle valve for operation.
Check and clean.
Replace.
Replace.
Check and adjust.
Clean.
Adjust or replace.
CARBURETOR
Complaint
Symptom and possible causes
Remedy
Complaint
Symptom and possible causes
Remedy
