2005-2006 Honda ATV TRX500FE/FM/TM FourTrax Foreman Factory Service Manual, Page 141Get this manual
CYLINDER HEADVALVE Using 60 interior cutter, remove 14 of the existing valve seat materialTOOLS: Interior cutter, 37.5 mm (45 IN) 07780-0014100 Interior cutter, 34 mm (45 EX) 07780-0014700 Cutter holder, 6.0 mm 07VMH-MBB0100 or equivalent commercially available in U.S.A
60 Using 45 seat cutter, cut the seat to the proper widthVALVE SEAT WIDTH: 1.2 mm (0.05 in) Make sure that all pitting and irregularities are removedSEAT WIDTH