Polaris 2012 Sportsman Forest 500 International, Service Manual

Page: 83 / 432

3.28
ENGINE
9923412 - 2012 Sportsman 400/500 and EFI Tractor Service Manual
© Copyright 2011 Polaris Sales Inc.
16. Remove valve and check where the Prussian Blue™
indicates seat contact on the valve face. The 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 it is
too high on the valve face. Use the 30
o
cutter to
lower the valve seat.
• If too low use the 60
o
or 75
o
cutter to raise the
seat. When 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
o
cutter
and re-check contact point on the valve face and
seat width after each cut.
NOTE: When using an interference angle, the seat
contact point on the valve will be very narrow, and is
a normal condition. Look for an even and continuous
contact point on the black marked area, all the way
around the valve face.
17. Clean all filings from the area with hot soapy water,
rinse, and dry with compressed air.
18. Lubricate the valve guides with clean engine oil, and
apply oil or water based lapping compound to the face
of the valve. Lapping is not required with an
interference angle.
19. Insert the valve into its respective guide and lap using
a lapping tool or a section of fuel line connected to the
valve stem.
20. Rotate the valve rapidly back and forth until the cut
sounds smooth. Lift the valve slightly off of the seat,
rotate 1/4 turn, and repeat the lapping process. Do
this four to five times until the valve is fully seated, and
repeat process for the other valve(s).
21. Clean cylinder head, valves, and camshaft oil supply
passage (A) thoroughly.
22. If oil passage blind plug was removed, apply
Crankcase Sealant (PN 2871557) or equivalent
sealer to the threads and install, torquing to 8 ft. lbs.
(11 Nm).

CAUTION: Do not allow sealant to enter oil passage.
23. Spray electrical contact cleaner into oil passage and
dry using compressed air.
Valve Seat Width:
Intake Std: .028” (.7 mm)
Limit: .055” (1.4 mm)
Exhaust Std: .039”(1.0 mm)
Limit: .071” (1.8 mm)
Seat
Width
Bottom - 60
o
or 75
o
Seat - 45
o
or 46
o
Top - 30
o
or 31
o
A