2006-2012 Honda TRX90 TRX90EX/X Service Manual, Page 100Get this manual
CYLINDER HEADVALVES
TROUBLESHOOTING
Eng ine top-end problems usually affect engine performanceThese problem can be diagnosed by compression test or by tracing engine noises to the top-end with sound ing rod stethoscope If the performance is poor at low speeds, check for white smoke the crankcase breather hoseIf the hose is smoky, check for seized piston ring (page 8-4 )Compression too low, hard starting or poor performance at low speed Valves:Incorrect valve adjustmentBurned or bent valveIncorrect valve tim ingBroken valve springUneven valve seating Cyl inder head:Leaking or damaged head gasketWarped or cracked cylinder head Loosen spark plug Worn cylinder, piston or piston rings (page 8-4) Compression too high, overheating or knocking Excessive carbon build-up on piston crown or on combustion chamber Excessive smoke Cylinder head:Worn valve stem or valve guideDamaged stem seal Worn cylinderpiston or piston rings (page 8-4) Excessive noise Cylinder head:Incorrect valve adjustmentSticking valve or broken valve springWorn or damaged cam chainWorn or damaged cam chain tensionerWorn cam sprocket teethWorn rocker arm andl or shaft Worn cylind er, piston or piston rings (page 8-4) Rough idle Low cylinder compression Intake air leak