Polaris Sportsman 400, Service Manual

Page: 102 / 381

ENGINE
3.33
VALVE SEAT RECONDITIONING, CONT.
1. Install pilot into valve guide.
2. Apply cutting oil to valve seat and cutter.
3. Place 46
°
cutter on the pilot and make a light cut.
4. Inspect the cut area of the seat.
S If the contact area is less than 75% of the cir-
cumference of the seat, rotate the pilot 180
°
and make another light cut.
S
If the cutter now contacts the uncut portion of
the seat, check the pilot. Look for burrs,
nicks, or runout. If the pilot is bent it must be
replaced.
S If the contact area of the cutter is in the same
place, the valve guide is distorted from im-
proper installation and must be replaced. Be
sure the cylinder head is at the proper temper-
ature and replace the guide.
S If the contact area of the initial cut is greater
than 75%, continue to cut the seat until all pits
are removed and a new seat surface is evi-
dent. NOTE: Remove only the amount of
material necessary to repair the seat surface.
5. To check the contact area of the seat on the valve
face, apply a thin coating of Prussian Blue
™
paste to
the valve seat. If using an interference angle (46
°
)
apply black permanent marker to the entire valve
face (A).
6. Insert valve into guide and tap valve lightly into place
a few times.
(A)