1985-1987 Honda TRX 250 Fourtrax 250 Service Manual, Page 66Get this manual
CYLINDER HEADV ALVES Inspect the width of each valve seatSTANDARD: 1.2 mm 10.05 inSERVICE LIMIT: 1.5 mm (0 .06 in If the seat is too wide, too narrow or has low spots, the seat must be ground
V ALV SEAT CUTTERS
Honda Valve Seat Cutters, grinder or equivalent valve seat refacing equipment ale recommended to correc worn valve
seatNOTE
Follow the re facemanufactu rer's operating instr uctions