HYOSUNG 2010 ST7 Service Manual page 263

9-7 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 pistons or cylinders.
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 clutch
1. Worn splines of countershaft or hub.
2. Worn teeth of clutch plates.
3. Distorted clutch plates, driven and drive.
4. Worn clutch release bearing.
5. Weakened clutch dampers.
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.
4. Worn or rubbing primary gears.
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 the primary driven gear.
Replace.
Replace.
Replace.
Replace.
Replace.
Replace.
Replace.
Replace.
Replace.
Replace.
Replace.