Valve Seat Reconditioning - Polaris Sportsman 400 Service Manual

VALVE SEAT RECONDITIONING

Valve Seat Inspection
Inspect valve seat in cylinder head for pitting, burnt spots, roughness, and uneven surface. If any of the above
conditions exist, the valve seat must be reconditioned. See Valve Seat Reconditioning, page 3.32. If the valve
seat is cracked the cylinder head must be replaced.
Cylinder Head Reconditioning
NOTE: Servicing the valve guides and valve seats requires special tools and a thorough knowledge of recondi-
tioning techniques. Follow the instructions provided in the cylinder head service tool kit.
CAUTION: Wear eye protection when performing cylinder head service. Valve guide replacement will require
heating of the cylinder head. Wear gloves to prevent burns.
Valve Guide Removal/Installation
1. Remove all carbon deposits from the combustion chamber, valve seat and valve guide area before attempting
to remove valve guides. CAUTION: Carbon deposits are extremely abrasive and may damage the valve
guide bore when guides are removed.
2. Place new valve guides in a freezer for at least 15 minutes while heating cylinder head.
3. Heat cylinder head in an oven or use a hot plate to bring cylinder head temperature to 212° F (100° C).
CAUTION: Do not use a torch to heat cylinder head or warpage may result from uneven heating. Head
temperature can be checked with a pyrometer or a welding temperature stick.
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ENGINE
3.31