Engine Unit Repair

Apply a light coat of Prussian blue (or white lead) to the valve face.

Lightly press the valve against the valve seat.

NOTICE:

Do not rotate the valve.

Check the valve face and seat according to the following procedure.

1. If blue appears 360° around the face, the valve is concentric.
   If not, replace the valve.
   

2. If blue appears 360° around the valve seat, the guide and face are concentric.
   If not, resurface the valve seat.
   

3. Check that the seat contact is in the middle of the valve face with the width below.
   

   Standard width:

   1.0 to 1.4 mm (0.039 to 0.055 in.)
   

If the seating is too high on the valve face, use 30° and 45°cutters to correct the seat.

Intake side:
If the seating is too low on the valve face, use 60°and 30°cutters to correct the seat.

Exhaust side:
If the seating is too low on the valve face, use 75°and 45°cutters to correct the seat.

Hand-lap the valve and valve seat with an abrasive compound.

After hand-lapping, clean the valve and valve seat.