Honda CRF450R 2009 Service Manual page 549

ENGINE LACKS POWER
1. Drive Tra in Inspection
Raise wheel off the ground and spin by hand.
Did the wheel spin freely?
NO Brake dragging
Worn or damaged wheel bearings
Benl axle shaft
Drive chain too light
YES - GO TO STEP 2.
2. Tire Pressure Inspection
Check tire pressure.
Is the
tire
pressures low?
YES _. Faulty valve core
• Punctured lire
NO - GO TO STEP 3.
3. Clutch Inspection
Accelerate rapidly from low to second.
Did the engine speed change accordingly when clutch is engaged?
NO Clutch slipping
Improperly adjusted clutch lever freeplay
Worn clutch discs/plates
Warped clutch discs/plates
Weak clutch springs
Slicking clutch lifter
Additive in engine oil
YES - GO TO STEP 4.
4. Engine Performance Inspection
Accelerate tighlly.
Did the engine speed increase?
NO Dirty air cleaner
Restricted fuel flow
Clogged muffler
Clogged fuel tank breather hose
Fast idle knob stuck open or damaged
Excessive carbon build-up in combustion chamber
YES - GO TO STEP 5.
5. Engine knocking Inspection
Accelerate or run at high speed,
Is there knocking ?
YES - Worn piston and cylinder
Use of poor quality fuel
Excessive carbon build-up in combustion chamber
Ignition timing too advance (Faulty ECM)
Lean fuel mixture
Faulty CKP sensor
Wrong type fuel
NO - GO TO STEP 6.
TROUBLESHOOTING
19-3