Honda CRF50F 2004-2015 Service Manual page 204

ENGINE LACKS POWER
1. Drive Train Inspection
Raise wheel off the ground and spin by hand.
Does the wheel spin freelr ?
NO _ . Brake dragging
• Worn or damaged w heel bearings
YES - GO TO STEP 2.
2. Tire Pressure Inspection
Check the tire pressure.
Is the tire pressure correct?
NO _ . Faulty tire valve
• Punctured tire
YES - GO TO STEP 3.
3. Clutch Inspection
Accelerate rapidly from low to second.
Does the engine speed change Bccordingl y when clutch is released?
NO _ . Clutch slipping
• Worn clutch d iscs/plates
• Warped clu t ch discs/plates
• Weak clutch spring
• Additive in engine oi l
YES - GO TO ST EP 4.
4. Engine Performance Inspection
Accelerate lightly.
Does the engine speed increase?
NO _ . Choke valve closed
• Clogged air cleaner
• Restricted fuel flow
• Clogged muffler
• Pinched fuel tank breather hose
YES - GO TO STEP 5.
5. Ignition Timing In spection
Check the ignition timing.
Is th e ignition timing normal?
NO _ . Faulty ignition control modu le
• Faulty ignition pulse generator
YES - GO TO STEP 6.
6. Cylinder Compression Inspection
Test cylinder compression.
Is the compression normal?
NO _ . Valve clearance too small
• Worn cylinder and piston ring
• Leaking head gasket
• Seized valve
• Improper valve timi ng
YES - GO TO STEP 7.
7. Carburetor Inspection
Check the carburetor for clogs.
Is the carburetor clogged?
YES - Ca rbur et or nOI serviced frequently enough
NO - GO TO STEP 8.
TROUBLESHOOTING
16-3