Polaris 2007 Sportsman 450 EFI, Service Manual

Page: 83 / 406

3.25
ENGINE
3
13. 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(B) 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 marker, all the way around the
valve face.
14. Clean all filings from the area with hot soapy water, rinse,
and dry with compressed air.
15. 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.
16. Insert the valve into its respective guide and lap using a
lapping tool or a section of fuel line connected to the valve
stem.
17. 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).
18. Clean cylinder head, valves, and camshaft oil supply
passage (A) thoroughly.
19. 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).
20. 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
CAUTION
Do not allow sealant to enter oil passage.
A