Suzuki UY125, Service Manual

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7-2 SERVICING INFORMATION
TROUBLESHOOTING
ENGINE
Complaint Symptom and possible causes Remedy
Engine will not
start, or is hard to
start. Compression too low
1. Out of adjustment valve clearance.
2. Worn valve guides or poor seating of valves.
3. Mistimed valves.
4. Excessively worn piston rings.
5. Worn-down cylinder bore.
6. Starter motor cranks too slow.
7. Poor seating of spark plug.
8. Gas leaks from the joint in crankcase, cylinder or
cylinder head.
Plugs not sparking
1. Fouled spark plug.
2. Wet spark plug.
3. Defective ignition coil.
4. Open or short in high-tension cord.
5. Defective pick-up coil or CDI unit.
6. Open or short circuited wiring connections.
7. Defective spark plug.
8. Defective spark plug cap.
No fuel reaching the carburetors
1. Clogged hole in the fuel tank cap.
2. Clogged or defective fuel pump.
3. Defective carburetor needle valve.
4. Clogged fuel hose or fuel filter.
Adjust.
Repair or replace.
Adjust.
Replace.
Replace or rebore.
See electrical section.
Retighten.
Repair or replace.
Clean.
Clean and dry.
Replace.
Replace.
Replace.
Repair or replace.
Replace.
Replace.
Clean or replace.
Clean or replace.
Replace.
Clean or replace.
Engine stalls often. 1. Fouled spark plug.
2. Defective pick-up coil or CDI unit.
3. Clogged fuel hose or fuel tank cap.
4. Clogged jets in carburetor.
5. Out of adjustment valve clearance.
6. Clogged exhaust pipe.
7. Open or short circuited wiring connection. Clean.
Replace.
Clean or replace.
Clean.
Adjust.
Clean.
Repair or replace.
Noisy engine. Excessive valve chatter
1. Too large valve clearance.
2. Weakened or broken valve spring.
3. Worn rocker arm or cam surface.
4. Worn and burnt camshaft bearing.
Noise seems to come from piston
1. Worn down piston or cylinder.
2. Fouled with carbon combustion chamber.
3. Worn piston pin or piston pin bore.
4. Worn piston rings or ring grooves.
Adjust.
Replace.
Replace.
Replace.
Replace.
Clean.
Replace.
Replace.
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