1997-2001 Honda TRX250 Fourtrax Recon Service Manual, Page 105Get this manual
CYLINDER HEADCYLINDERPISTON
TROUBLESHOOTING
Engi ne top-end problems usua ll affect engine performanceThese problem ca be diagnosed by compression test or by tracing engine noises to the top -end with sounding rod steth oscope If the performance is poor at low speeds, check for white smoke in the cr ankcase breather tube If the tube is smoky, check for seized piston ri ngLow compression Valves- Incorrect va lve adjustmentBurned or bent valve Incorrect valve timing Weak valve spring Cylinder head:Leaking or damag ed head gasketWarped or racked cy linder head Cylinder piston Worn cylinder or piston ring High compression Excess ive carbon build-up on piston crown or on combustion chamber Excessive smoke Worn valve st em or valve guide Damaged stem seal Worn cy linde r, piston or piston rings Improper insta llatio of piston rings Scored or scratched piston or cylinder wall Excessive noise Incorrect valve adjustment Stick ing valve or broken valve spri ng Worn or damaged push rod andor cam follwer Worn rocker arm andor shaft Rough idle Low cylinder comp ression Intake air leak Overheating Excessive carbon build-up on the piston head or on com bustion chamber Knocking or abnormal noise Worn piston and cylinder Excessive carbon bui ld-up