Suzuki VL125 Service Manual page 211

9-4 SERVICING INFORMATION
Complaint
Transmission jumps
out of gear.
Engine idles poorly.
Engine runs poorly in
high-speed range.
Exhaust smoke is
dirty or thick.
Engine lacks power.
Symptom and possible causes
1. Worn gear.
2. Worn or distorted gearshift fork.
3. Weakened gearshift stopper spring.
4. Worn gearshift pawl.
1. Valve clearance out of adjustment.
2. Improper valve seating.
3. Worn valve guide.
4. Worn camshaft.
5. Excessive spark plug gap.
6. Defective ignition coil.
7. Defective generator.
8. Defective ignitor unit.
9. Incorrect float chamber fuel level.
10. Clogged carburetor jet.
1. Weak valve spring.
2. Worn camshaft.
3. Insufficient spark plug gap.
4. Mistimed valves.
5. Ignition not advanced sufficiently due to poorly work-
ing timing advance circuit.
6. Defective ignition coil.
7. Defective generator.
8. Defective ignitor unit.
9. Low float chamber fuel level.
10. Dirty air cleaner element.
11. Clogged fuel hose, resulting in inadequate fuel supply
to carburetor.
1. Excessive amount of engine oil.
2. Worn cylinder.
3. Worn piston ring.
4. Worn valve guide.
5. Scored or scuffed cylinder wall.
6. Worn valve stem.
7. Defective valve stem oil seal.
8. Worn oil ring side rail.
1. Insufficient valve clearance.
2. Weak valve spring.
3. Mistimed valves.
4. Worn cylinder.
5. Worn piston ring.
6. Improper valve seating.
7. Fouled spark plug.
8. Incorrect spark plug.
9. Clogged carburetor jet.
10. Incorrect float chamber fuel level.
11. Dirty air cleaner element.
12. Air leakage from intake pipe.
13. Excessive amount of engine oil.
Remedy
Replace.
Replace.
Replace.
Replace.
Adjust.
Repair or replace.
Replace.
Replace.
Adjust or replace.
Replace.
Replace.
Replace.
Adjust float height.
Clean.
Replace.
Replace.
Regap or replace.
Adjust.
Replace ignitor unit.
Replace.
Replace.
Replace.
Adjust float height.
Clean or replace.
Clean and prime.
Check level and drain.
Rebore or replace.
Replace.
Replace.
Replace.
Replace valve.
Replace.
Replace oil ring.
Adjust.
Replace.
Adjust.
Replace.
Replace.
Repair or replace.
Clean or replace.
Replace.
Clean.
Adjust float height.
Clean or replace.
Tighten or replace.
Check level and drain.