1999-2002 TRX400EX Fourtrax Service Manual, Page 97Get this manual
CYLINDER HEADVALVE
VALVE GUIDE REPLACEMENT
Chill new valve guides in the freezer section of refrigerator for about an hourHeat the cylinder head to 130140C (275290F) with hot plate or ovenDo not heat the cylinder head beyond 150" (300F)Use temperature indicator sticks, available from welding supply stores, to be sure the cylinder head is heated to the proper temperature
Wear heavy gloves to avoid burns when handling the heated cylinder headCAUTION: Using torch to heat the cylinder head may cause wamaqeSupport the cylinder head and drive the valve guides out of the cylinder head from the combustion chamber sideTOOL Valve guide driver, 5.5 mm
VALVE GUIDE RIVER
07742- 0010100
Install new O-rings onto the new valve guidesDrive the new valve guides in the cylinder head from the camshaft side while the cylinder head is still heatedTOOL Valve guide driver, 5.5 mm