2004-2007 Honda Aquatrax ARX1200N3/T3/T3D Factory Service Manual, Page 317Get this manual
CYLINDER HEADVALVE Use 60! interior cutter to remove the bottom 14 of the existing valve seat materialTOOLS: Interior cutter, 34 mm (IN) 07780-0014700 Interior cutter, 30 mm (EX) 07780-0014000 Cutter holder, mm 07781-0010400 or equivalent commercially available in U.S.A(Neway 111, intake and exhaust) (Neway pilot, 100-5.0 mm) OLD SEAT WIDTH
Using 45! seat cutter, cut the seat to the proper widthMake sure all pitting and irregularities are removedRefinish if necessary