Suzuki DL650 Service Manual page 405

9-6 SERVICING INFORMATION
NOISY ENGINE
Symptom, possible causes and remedy
1) Excessive valve chatter
Too large valve clearance.
Weakened or broken valve springs.
Worn tappet or cam surface.
Worn and burnt camshaft journal.
2) Noise seems to come from piston
Worn down pistons or cylinders.
Combustion chambers fouled with carbon.
Worn piston pins or piston pin bore.
Worn piston rings or ring grooves.
3) Noise seems to come from cam chain
Stretched chain.
Worn sprockets.
Tension adjuster not working.
4) Noise seems to come from clutch
Worn splines of countershaft or hub.
Worn teeth of clutch plates.
Distorted clutch plates, driven and drive.
Worn clutch release bearing.
Weakened clutch dampers.
5) Noise seems to come from crankshaft
Rattling bearings due to wear.
Worn and burnt big-end bearings.
Worn and burnt journal bearings.
6) Noise seems to come from transmission
Worn or rubbing gears.
Worn splines.
Worn or rubbing primary gears.
Worn bearings.
7) Noise seems to come from water pump
Too much play on pump shaft bearing.
Worn or damaged impeller shaft.
Worn or damaged mechanical seal.
Contact between pump case and impeller.
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.