2006-2014 Honda FourTrax ATV TRX250 EX TRX250X Service Manual, Page 130Get this manual
CYLINDER HEADVALVECAMSHAFT Remove the new valve guides from the freeze rBe sure to install the stopper ring into the valve guide rooveWhile the cylinder head is still heated, drive each valve guide into the cylinder head from the head cover side until the stopper ring is contacted the cylinder head TOOL: Valve guide driver, 5.5 mm 077420010100
VALVE GUIDE DRIVER
Let the cylinder head cool to room temperature
Use cutting oil on the reamer during this operationTake care not to tilt or learn the reamer in the guide while reaming
Ream the new valve guidesInsert the reamer from the combustion chamber side of the cylinder head and always rotate the reamer clockwise TOOL: Valve guide reamer, 5.5 mm 079842000001 or 079842000000 (U.S.Aonly)
VALVE GUIDE REAMER
Clean the cylinder head tho roughly to remove any metal particles after reaming and reface the valve seat (page 8-15)