Suzuki DL650 Service Manual page 407

9-8 S E R V I C I N G INFORMATION
ENGINE LACKS POWER
Symptom, possible causes and remedy
1) Defective engine internal/electrical parts
Loss of valve clearance.
Weakened valve springs.
Valve timing out of adjustment.
Worn piston rings or cylinders.
Poor seating of valves.
Fouled spark plugs.
Incorrect spark plugs.
Clogged injectors.
TP sensor out of adjustment.
Clogged air cleaner element.
Imbalanced throttle valve synchronization.
Sucking air from throttle valve or vacuum hose.
Too much engine oil.
Defective fuel pump or ECM.
Defective CKP sensor and ignition coils.
Symptom, possible causes and remedy
2) Defective control circuit or sensor
Low fuel pressure.
Defective TP sensor.
Defective IAT sensor.
Defective CKP sensor.
Defective GP switch.
Defective IAP sensor.
Defective ECM.
lmbalanced throttle valve synchronization.
TP sensor out of adjustment.
Defective STP sensor and/or STVA.
Adjust.
Replace.
Adjust.
Replace.
Repair.
Clean or replace.
Adjust or replace.
Clean or replace.
Adjust.
Clean or replace.
Adjust.
Retighten or replace.
Drain out excess oil.
Replace.
Replace.
Repair or replace.
Replace.
Replace.
Replace.
Replace.
Replace.
Replace.
Adjust.
Adjust.
Replace.