Suzuki RM-Z450 Owner's Service Manual page 59

3-4 TROUBLESHOOTING
Complaint
Engine lacks power. Defective engine internal parts
Engine overheats
Dirty or heavy
exhaust smoke
Symptom and possible causes
• Loss of tappet clearance
• Weakened valve springs
• Valve timing out of adjustment
• Worn piston ring or cylinder
• Poor seating of valves
• Fouled spark plug
• Incorrect spark plug
• Too much engine oil
Other factors
• Defective carburetor
• Sucking air from intake pipe
• Clogged air cleaner element
• Clogged muffler
Defective engine internal parts
• Heavy carbon deposit on piston crowns
• Not enough oil in the engine
• Defective oil pump or clogged oil circuit
• Sucking air from intake pipes
• Use incorrect engine oil
Other factors
• Mixture too rean
• Ignition timing is too advanced due to defective tim-
ing advance system (Pick-up coil, Throttle position
sensor and CDI unit)
• Defective cooling system
• Drive chain is too tight
• Too much engine oil in the engine
• Worn piston ring or cylinder
• Worn valve guides
• Scored or scuffed cylinder wall
• Worn valves stems
• Defective stem seal
• Worn oil ring side rails
Remedy
Adjust
Replace
Adjust
Replace
Repair
Clean or replace
Adjust or replace
Drain out excess oil
See carburetor section
Retighten or replace
Clean or replace
Clean or replace
Clean
Add oil
Replace or clean
Retighten or replace
Change
Carburetor tuning
Replace
See radiator section
Adjust
Drain out excess oil
Replace
Replace
Replace
Replace
Replace
Replace