1987 Honda Fourtrax TRX 250X Service Manual, Page 71Get this manual
CYLINDER HEADIVAlVES Apply thin coating of Prussian Blue to the valve seatPress the valve through the valve guide and onto the seat to make cleaf patternNOTE The location of Ihe valve seat in relation to the valve face is very important for good sealingIf the contact area is too high on the valve, the S8al must be lowered using 32 degree flat cutter
11) CONTACT TOO HIGH
"- OLD SEAT WIDTH (2)
If the contact 8rea is too Iowan the valv8, the seat must be raised using 60 degree inner cutter