Checking / repairing the valve seat of the gas distribution mechanism

1. Measure the width of the contact surface of the valve and the valve seat using a valve lapping compound. If the measured value is not correct (1.37-1.84mm), bore the valve seat using a reamer with a 45°chamfer angle.



2. Verify that the valve seat is centered on the valve surface.

• If the fit position is too high, correct the fit using a reamer with a 70°bevel angle (intake valve / exhaust valve) and reamers with a chamfer angle of 45°.
• If the fit is too low, correct the fit using reamers with 20°and 45°chamfer angles (inlet valve) or one 45°sweep (Exhaust valve).

3. Check the valve seat for settlement. To do this, measure the height of the protrusion (length L) valve stem using a standard length valve. If the measured value is not correct, replace the cylinder head with a new one.

Note:

Valve stem protrusion (size L):

• intake: 48.93-50.17 mm
• outlet: 48.87-50.11 mm