2001 Polaris Sportsman 400-500 DUSE and H.O. Service Manual, Page 103Get this manual
VALVE SEAT RECONDITIONING, CONT7Remove valve and check where the Prussian Blue 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& If the indicated seat contact is at the top edge of the valve face and contacts the margin area(B) it is too high on the valve faceUse the 30 cutter to lower the valve seat& If too low use the 60 or 75 cutter to raise the seatWhen contact area is centered on the valve face, measure seat width& If the seat is too wide or uneven, use both top and bottom cutters to narrow the seat& If the seat is too narrow, widen using the 45 cutter and re-check contact point on the valve face and seat width after each cut