1987 Honda Fourtrax TRX 250X Service Manual, Page 70Get this manual
CYLINDER HEADVALVES Honda Valve Seat Cutters, grinder or eQuivalent valve seat refacing eQuipment are recommended to correct worn valve seatNOTE Follow the refacer manufacturer'S operating instructions
RE FACING
Use 45 degree cutter to remove any roughness or irregularities from the seat NOTE Aeface the seat with 45 degree cutter when valve guide is replacedUse 32 degree cutler to remove the top 14 of the existing valve seat material