2005-2006 Honda ATV TRX500FE/FM/TM FourTrax Foreman Factory Service Manual, Page 443Get this manual
TROUBLESHOOTING 7Carburetor Inspection Check the carburetor for cloggingAre the carburetor passages clear? NO YESCarburetor not serviced frequently enoughGO TO STEP 8
8Spark Plug Inspection Remove and inspect the spark plugIs the spark plug in good condition? NO YESPlugs not serviced frequently enough Incorrect spark plug usedGO TO STEP 99Engine Oil Inspection Check the oil level and conditionIs the engine oil at the correct level and in good condition? NOOil level too high Oil level too low Contaminated oil YESTO STEP 1010Valve Train Lubrication Inspection Remove the cylinder head cover and inspect lubricationIs the valve train properly lubricated? NO YESClogged oil passage Clogged oil orificeTO STEP 1111Engine Knocking Inspection Accelerate or run at high speedfe the YES engine knocking? and cylinder Worn piston Use of poor quality fuel Excessive carbon build-up in combustion chamber Ignition timing too advanced (Faulty ECM) Lean fuel mixture