2004-2009 Honda TRX450R/TRX450ER Service Manual, Page 520Get this manual
TROUBLESHOOTING
POOR PERFORMANCE AT HIGH SPEED
1Fuel Line Inspection Disconnect the fuel line at the carburetorDoes fuel flow freely? YES NOGO TO STEP 2- Clogged fuel line Clogged fuel fill cap breather hose Faulty fuel valve Clogged fuel strainer 2Carburetor Inspection Check carburetor for cloggingIs the carburetor clogged? YES NOCarburetor not serviced frequently enoughGO TO STEP 3
3Valve Timing Inspection Check valve timingIs the valve timing correct? NO YESCamshaft not installed properlyGO TO STEP 4
4Ignition Tinning Inspection Check ignition timingIs the ignition timing correct? NO YESFaulty ignition control module (ICM) Faulty ignition pulse generatorGO TO STEP 55Valve Spring Inspection Check valve springsAre the valve springs weak? YESFaulty valve springs