1998-2001 Honda Fourtrax Foreman TRX450S, TRX450ES Factory Service Manual, Page 134Get this manual
CYLINDER HEAD lCVUND'ERPISTON VALVE SEAT JNSPECTJONREFACING Clean he intake and exhaust va lves thoro ug hly remo ve ca rbon de positsApp ly light coating of Pru ssian Bl ue to the alve seatsTap the valves and seats using ru bbe hose Or other hand-lappin too lHAND LAPPIN TOOL
Remove and jn, pect the valv ess
CAUTION;
The valves canno't be gKOundII it valv, face ;s burned or badJy worn or if it contacts the seat unevenly, replace the valve
Inspect the width of each valve seat
STANDARD: 1:.2' mrn 10.05 inl SERVICE UMfT: 1.5 mm 10.G6 inl
If he seat is too wide, too narrow has low spots, the seat ust be ro und
VALVE SEAT IREFACING