2004-2009 Honda TRX450R/TRX450ER Service Manual, Page 209Get this manual
CYLINDER HEADVALVE INTAKE VALVE LIFTER Check the valve lifter for scoring, scratches or abnormal wearMeasure each valve lifter O.DSERVICE LIMIT: 25.97 mm (1.022 in)
Check the valve lifter bore for scoring, scratches or abnormal wearMeasure each valve lifter bore I.DSERVICE LIMIT: 26.04 mm (1.025 in)
DECOMPRESSOR CAM Check the cam and weight for excessive wear or damageCheck the weight spring for damage