Service manual
ENGINE
1. Install pilot into valve guide.
5. To check the contact area of the seat on the valve face,
apply a thin coating of PrussianBluetpaste to the valve
seat. If using an interference angle (46°) apply black
marker to the entire valve face (A).
6. Insert valve into guide and tap valve lightly into place a
few times.
7. Remove valve and check where the Prussian Bluit or
black marker 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 (A).
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. If the contact area is
less than 75% of the circumference of the seat, rotate the
pilot 180° and make another light cut.
If the cutter now contacts the uncut portion of the seat,
check the pilot. Look for burrs, nicks, or run out. If the pilot
is bent it must be replaced.
If the contact area of the cutter is in the same place, the
valve guide is distorted from improper installation and
must be replaced. Be sure the cylinder head is at the
proper temperature and replace the guide.
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 evident.
NOTE: Remove only the amount ofmaterial necessary to
repair the seat surface.
◎ 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° cutter to lower the valve
seat.
◎ If too low use the 60° or 75° 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° cutter and re-check contact point on the valve
face and seat width after each cut.
4.16