Polaris Sportsman 400 Service Manual page 101

ENGINE
VALVE SEAT RECONDITIONING, CONT.
Follow the manufacturers instructions provided with
the valve seat cutters in the Cylinder Head Recondi-
tioning Kit (PN 2200634). Abrasive stone seat re-
conditioning equipment can also be used. Keep all
valves in order with their respective seat.
NOTE: Valve seat width and point of contact on the
valve face is very important for proper sealing. The
valve must contact the valve seat over the entire cir-
cumference of the seat, and the seat must be the prop-
er width all the way around. If the seat is uneven, com-
pression leakage will result. If the seat is too wide, seat
pressure is reduced, causing carbon accumulation
and possible compression loss. If the seat is too nar-
row, heat transfer from valve to seat is reduced and the
valve may overheat and warp, resulting in burnt
valves.
1. When thoroughly heated, place cylinder head on blocks of wood which will allow the old guides to be removed.
2. Using valve guide driver, drive guides out of the cylinder head from the combustion chamber side. Be careful
not to damage guide bore or valve seat when removing guides.
3. Place cylinder head on cylinder head table.
NOTE: Be sure cylinder head is still at 212° F
(100° C) before installing new guides.
4. Place a new guide in the valve guide installation
tool and press guide in to proper depth. Check
height of each guide above the cylinder head (A).
NOTE: The guide can also be driven in to the
proper depth. Inspect the guide closely for cracks
or damage if a driver is used.
Valve Guide Height:
.689-.709I (17.5-18.0 mm)
Reaming The Valve Guide
5. Allow cylinder head to cool to room temperature.
Apply cutting oil to the reamer. Guides should be
reamed from the valve spring side of the cylinder
head. Ream each guide to size by turning the
reamer clockwise continually. Continue to rotate
reamer clockwise during removal of the tool.
6. Clean guides thoroughly with hot soapy water and
a nylon brush. Rinse and dry with compressed air.
Apply clean engine oil to guides.
3.32
- projex@inbox.lv -
Too
Wide
Good
Uneven
A
Valve Guide Installed Height
Too
Narrow