HYOSUNG MS3 250 Sercie Manual page 223

9-5 SERVICING INFORMATION
Complaint
Noisy engine.
Symptom and possible causes
Excessive valve chatter
1. Too large tappet clearance.
2. Weakened or broken valve springs.
3. Worn tappet or cam surface.
4. Worn and burnt camshaft journal.
Noise seems to come from piston
1. Worn down piston or cylinder.
2. Combustion chambers fouled with carbon.
3. Worn piston pins or piston pin bore.
4. Worn piston rings or ring grooves.
Noise seems to come from cam chain
1. Stretched chain.
2. Worn sprockets.
3. Tension adjuster not working.
Noise seems to come from crankshaft
1. Rattling bearings due to wear.
2. Worn and burnt big-end bearings.
3. Worn and burnt journal bearings.
Noise seems to come from transmission
1. Worn or rubbing gears.
2. Worn splines.
3. Worn bearings.
Noise seems to come from water pump
1. Too much play on pump shaft bearing.
2. Worn or damaged impeller shaft.
3. Worn or damaged mechanical seal.
4. Contact between pump case and impeller.
Remedy
Adjust.
Replace.
Replace.
Replace.
Replace.
Clean.
Replace.
Replace.
Replace.
Replace.
Repair or replace.
Replace.
Replace.
Replace.
Replace.
Replace.
Replace.
Replace.
Replace.
Replace.
Replace.