2005-2008 Honda ATV TRX500FA/FGA Fourtrax, Rubicon Factory Service Manual, Page 176Get this manual
CYLINDER HEADVALVECAMSHAFT REFACING Follow the refacer manufacturer's operating instructions Be careful not to grind the seat more than necessary45
If the contact area is too high on the valve, the seat must be lowered using 32 flat cutterIf the contact area is too low on the valve, the seat must be raised using 60 interior cutter
CONTACT TOO HIGH
32 CONTACT TOO LOW
60 Using 45 seat cutter, remove any roughness or irregularities from the seatROUGHNESS