Lap the valve to the seat using a lapper, once the seat
width and outside diameter are within the ranges specified
Put a little coarse grinding compound on the face of the
valve in a number of places around the valve head.
Spin the valve against the seat until the grinding com-
pound produces a smooth, matched surface on both the
seat and the valve.
Repeat the process with fine grinding compound.
[B] Valve Seat
The seating area should be marked about in the middle
of the valve face.
If the seat area is incorrect place on the valve, be sure
to check the valve is the correct part. If it is, it may have
been refaced too much replace the valve.
Be sure to remove all grinding compound before assem-
When the engine is assembled, be sure to adjust the valve
clearance (see Valve Clearance Adjustment in the Peri-
odic Maintenance chapter).
Valve Head Thickness Inspection
Measure the thickness of valve head.
Valve Head Thickness [A]
Exhaust valve 0.8 mm (0.031 in.)
0.5 mm (0.020 in.)
Exhaust valve 0.5 mm (0.020 in.)
0.25 mm (0.010 in.)
If it is under the service limit, replace the valve.
Valve Stem Bend Inspection
Support the valve at both ends of the straight stem por-
tion, and set a dial gauge against the center of the stem.
Turn the valve and read the variation in the dial gauge [A].
Valve Stem Bend
TIR 0.01 mm (0.0004 in.) or less
Service Limit: TIR 0.05 mm (0.002 in.)
If it is bent over the service limit, replace the valve.
ENGINE TOP END 4-29