2007-2009 Honda TRX300EX TRX300X service manual, Page 125Get this manual
CYLINDER HEADVALVE VALVE SPRING
Check the valve spri ngs for fatigue or damageMeasure the valve spring free length
SERVICE LIMITS: INEX: Inner: 37.8 mm (1.49 in) Outer: 39.8 mm (1.57 in)
VALVEIVALVE GUIDE
Check that the valve moves smoothly in the guideCheck the valve for bending, burning or abnormal wearMeasure each valve stem 0.0and record it
SERVICE LIMITS: IN: 5.45 mm (0.215 in) EX: 5.43 mm (0.214 in)
Ream the guides to remove any carbon build-up before measuring the guideInsert the reamer from the combustion chamber side of the head and always rotate the reamer clockwise
TOOL: Valve guide reamer, 5.5 mm
07984-2000001 or 079842000000 (U.S.Aonly)