2005-2009 Honda TRX400EX/TRX400X Service Manual, Page 119Get this manual
CYLINDER HEADVALVE
TROUBLESHOOTING
Engine top -end prob lems usually affect eng ine performanceThese problems can be diagnosed by compression test, or by tracing top-end noise with sounding rod stethos cope If the performance is poor at low speeds, check for white smoke in the crankcase reather hoseIf the hose is smoky, check for seized piston ring (page 9-2) Compression too low, hard starting or poor performance at low speed ValvesIncorrect va lve adjustmentBurned or bent va lveInco rrect valve timingWeak valve springUn even valve seatingValve stuck open Cylinder headLeaki ng or damaged cylinder head gasketWarped or racked cylin der headLoose spark lu Cylin erpiston problem (page 9-3) Compression too high Excessive carbon build-up on piston head or combustion chamber Worn or damaged decompressor system Excessive smoke Worn valve stem va lve guide Damaged stem seal Cylinderpiston prob lem (page 9-3) Excessive noise Incorrect va lve adjustm ent Sticking va lve or broken va lve spring Excessive worn va lve seat Worn damaged camshaft Worn rock er arm andor sh aft Worn rocker arm fo ll ower and valve stem end Worn cam sprocket teeth Worn cam cha Worn or damag ed cam chai tensioner Cyli nder piston prob lem (page 9-3) Rough idle Low cy lin der compression