2010 Polaris Sportsman 850 Service Manual, Page 130Get this manual

2010 Polaris Sportsman 850 Service Manual, Page 130

ENGINE Valve Seat Reconditioning Valve seat reconditioning should be performed by technician proficient in cylinder head
the valve seat is cracked the cylinder head must be replacedValve seat width and point of contact on the valve face is very
important for proper sealingThe valve must contact the valve seat over the entire circumference of the seat, and the seat
must be the proper width all the way aroundIf the seat is uneven, compression leakage will resultIf the seat is too wide,
seat pressure is reduced, causing carbon accumulation and possible compression lossIf the seat is too narrow, heat transfer
from valve to seat is reducedThe valve may overheat and warp, resulting in burnt valves Insert valve into guide and tap valve
lightly into place few timesRemove 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