2003 Polaris ATV Trail Boss 330 Factory Service Manual, Page 65Get this manual
ENGINE VALVE SEAT RECONDITIONING CONT'D 3Place 46 cutter on the pilot and make light cut6Insert valve into guide and tap valve lightly into place few times7Remove valve and check where the Prussian Bluet or black marker indicates seat contact on the valve faceThe valve seat should contact the middle of the valve face or slightly above, and must be the proper width (A)
4Inspect the cut area of the seatG If the contact area is less than 75 of the circumference of the seat, rotate the pilot 180 and make another light cutG If the cutter now contacts the uncut portion of the seat, check the pilotLook for burrs, nicks, or runoutIf the pilot is bent it must be replacedG If the contact area of the cutter is in the same place, the valve guide is distorted from improper installation and must be replacedBe sure the cylinder head is at the proper temperature and replace the guideG If the contact area of the initial cut is greater than 75, continue to cut the seat until all pits are removed and new seat surface is evidentNOTE: Remove only the amount of material necessary to repair the seat surface5To check the contact area of the seat on the valve face, apply thin coating of Prussian Bluet paste to the valve seatIf using an interference angle (46) apply black marker to the entire valve face (A)