Valve Seat: Service and Repair

1. Bore out old seat until it collapses. Set machine depth stop so that bore cannot contact bottom face of seat recess in cylinder head.
2. Ream cylinder head recess. Reaming bore for service valve seat
Oversize 0.5 mm (0.020 inch):
Intake: 38.000 - 38.016 mm (1.4961 - 1.4967 inch)
Exhaust: 32.700 - 32.716 mm (1.2874 - 1.2880 inch)

NOTE: Use the valve guide center for reaming to ensure that the valve seat will have the correct fit.





3. Heat cylinder head to 120 to 140° C (248 to 284° F).
4. Press fit valve seat until it seats on the bottom.
5. Cut or grind valve seat using suitable tool at the specified dimensions.
6. After cutting, lap valve seat with abrasive compound.





7. Check valve seating condition.
^ The seat face angle "alpha" for both the intake and exhaust is 44° 53' - 45° 07'.
^ The contacting width "w" is 1.48 - 1.63 mm (0.0583 - 0.0642 inch) for the intake valve and 1.8 - 2.0 mm (0.071 - 0.079 inch) for the exhaust valve.