7-2
SERVICING INFORMATION
TROUBLESHOOTING
ENGINE
Complaint
Symptom and possible causes
Remedy
Engine will not
Compression too low
start, or is hard to
1. Worn cylinder.
Rebore or replace.
start.
2. Worn piston ring.
Replace.
3. Stiff piston ring.
Repair or replace.
4. Gas leaks from the joint in crankcase, cylinder or
Repair or replace.
cylinder head.
5. Damaged read valve
Replace.
6. Loose spark plug.
Tighten.
7. Broken, cracked or damaged piston.
Replace.
Spark plug not sparking
1. Damaged spark plug.
Replace.
2. Damaged spark plug cap.
Replace.
3. Fouled spark plug.
Clean or replace.
4. Wet spark plug.
Clean and dry or replace.
5. Defective ignition coil.
Replace.
6. Defective pick-up coil.
Replace.
7. Open or short in high-tension cord.
Replace.
8. Defective ignition switch.
Replace.
No fuel reaching the carburetor
1. Clogged hole in the fuel tank cap.
Clean or replace.
2. Clogged or defective fuel valve.
Clean or replace.
3. Clogged or defective fuel pump.
Clean or replace.
4. Defective carburetor needle valve.
Replace.
5. Clogged fuel hose.
Clean or replace.
6. Clogged fuel filter.
Clean or replace.
Engine stalls easily.
1. Fouled spark plug.
Clean or replace.
2. Defective pick-up coil or CDI unit.
Replace.
3. Clogged fuel hose or fuel tank cap.
Clean or replace.
4. Clogged carburetor jets.
Clean.
5. Clogged exhaust pipe.
Clean.
6. Damaged cylinder head gasket.
Replace.
Engine is noisy.
Noise appears to come from piston
1. Worn down piston.
Replace.
2. Worn cylinder.
Replace.
3. Carbon built-up in the combustion chamber.
Clean.
4. Worn piston pin, bearing or piston pin bore.
Replace.
5. Worn piston rings or ring grooves.
Replace.
Noise seems to come from clutch
1. Worn or slipping drive belt.
Replace.
2. Worn rollers in the movable drive face.
Replace.
Noise seems to come from crankshaft
1. Rattling bearing.
Replace.
2. Worn or burnt crankshaft bearings.
Replace.
3. Worn or burnt big-end bearing.
Replace.
Noise seems to come from final gear box
1. Worn or rubbing final gears.
Replace.
2. Worn splines.
Replace.
3. Worn or damaged bearings of driveshaft or rear axle
Replace.
shaft.
Clutch slips.
1. Worn or damaged clutch shoes.
Replace.
2. Weakened movable driven face spring.
Replace.
3. Worn clutch housing.
Replace.
4. Worn or slipping drive belt.
Replace.
Summary of Contents for UG110 2021
Page 1: ...UG110 9 9 5 0 0 1 1 1 8 0 0 1 E...
Page 27: ...2 14 PERIODIC MAINTENANCE...
Page 147: ...6 6 ELECTRICAL SYSTEM 6 7 6 7 6 8 6 8 TROUBLESHOOTING...
Page 198: ...Printed in Japan Y TK...
