Suzuki GN125F Service Manual page 129

TROUBLESHOOTING
ENGINE
Complaint
Engine will not start
or is hard to start.
Engine stalls easily
Noisy engine
Slipping clutch.
SERVICING INFORMATION
Symptom and possible causes
Compression too low
1. Valve clearance out of limit.
2. Worn valve guides or poor seating of valves.
3. Valves mistiming.
4. Piston rings excessively worn.
5. Worn-down cylinder bore.
6. Poor seating of spark plug.
7. Starting motor cranks but too slowly.
Plug not sparking
1. Fouled spark plug.
2. Wet spark plug.
3. Defective trigger coil.
4. Defective ignitor unit.
5. Defective ignition coil.
No fuel reaching the carburetor
1. Clogged hole in the fuel tank cap.
2. Clogged or defective fuel cock.
3. Defective carburetor float needle valve.
4. Clogged fuel pipe.
5. Clogged fuel filter.
1. Fouled spark plug.
2. Defective trigger coil.
3. Defective ignitor unit.
4. Clogged fuel pipe.
5. Clogged jets in carburetor.
6. Valve clearance out of limit.
7. Clogged fuel filter.
Excessive valve chatter
1. Valve clearance too large.
2. Weakened of broken valve springs.
3. Worn down rocker arm or rocker arm shaft.
Noise appears to come from piston
1. Piston or cylinder worn down.
2. Combustion chamber fouled with carbon.
3. Piston pin or piston pin bore worn.
4. Piston rings or ring groove worn.
Noise seems to come from clutch
1. Worn splines of countershaft or hub.
2. Worn teeth of clutch plates.
3. Distorted clutch plates, driven and drive.
4. Clutch damper weakened.
Noise seems to come from crankshaft
1. Worn of burnt bearings.
2. B g-end bearings worn and burnt. i
3. Thrust clearance too large.
Noise seems to come from transmission
1. Gears worn of rubbing.
2. Badly worn splines.
3. Primary gears worn or rubbing.
4. Badly worn bearings.
1. Clutch control out of limit or loss of play.
2. Weakened clutch springs.
3. Worn or distorted pressure plate.
4. Distorted clutch plates, driven and drive.
7-1
Remedy
Adjust.
Repair or replace.
Adjust.
Replace.
Replace or rebore.
Retighten.
Consult "electrical complaints"
Clean or replace.
Clean and dry.
Replace.
Replace.
Replace.
Clean.
Clean or replace.
Replace.
Clean or replace.
Clean or replace.
Clean.
Replace.
Replace.
Clean.
Clean.
Adjust.
Clean or replace.
Adjust.
Replace.
Replace.
Replace.
Clean.
Replace.
Replace.
Replace.
Replace.
Replace.
Replace.
Replace.
Replace.
Replace.
Replace.
Replace.
Replace.
Replace.
Adjust.
Replace.
Replace.
Replace.