Honda TRX450R Service Manual page 518

TROUBLESHOOTING
7. Cylinder Compression Inspection
Test cylinder compression.
Is the compression low?
YES - • Valve clearance too small
• Valve stuck open
• Worn cylinder and piston rings
• Damaged cylinder head gasket
• Seized valve
• Improper valve timing
• Faulty decompressor cam
NO - GO TO STEP 8.
8. Carburetor Inspection
Check carburetor for clogging.
Is the carburetor clogged?
YES - • Carburetor not serviced frequently enough
• Carburetor dirty
• Dirt getting past air cleaner
NO - GO TO STEP 9.
9. Spark Plug Inspection
Remove and inspect spark plug.
Is the spark plug fouled or discolored?
YES - • Plug not serviced frequently enough
• Incorrect spark plug used
• Incorrect spark plug gap
NO - G O TO STEP 10.
10. Engine Oil Inspection
Check oil level and condition.
Is the oil level correct and in good condition?
YES - G O TO STEP 11.
NO - • Oil level too high
• Oil level too low
• Contaminated oil
11. Lubrication Inspection
Remove cylinder head cover and inspect lubrication.
Is the valve train lubricated properly?
NO - • Faulty oil pump
• Faulty pressure relief valve
• Clogged oil passage
• Clogged oil strainer
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