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34) Inspection of Valve Seat
1.
Remove carbon built up on the valve.
2.
Apply thin coat of red lead on the valve seat.
Use valve lapper 1 (commercially available item) as
3.
shown to push valve 2 onto valve seat lightly.
4.
Measure width of area where valve face contacted with
valve seat a that can be identified with red lead adhered
to valve face. Correct valve seat if contact area is above or
below the center or contact area of valve seat is over
specified limit.
Valve Seat Contact Width a : Standard value
Intake and Exhaust Sides : 0.8 mm (0.0315 in)
Functional Limit :
Intake and Exhaust Sides : 1.8 mm (0.0709 in)
· Thinly apply lapping compound on the valve
seat, and perform lapping by rotating and
tapping valve lapping tool.
· Use coarse lapping compound first, then
medium and fine in this order.
· When changing abrasive compound to finer one,
remove present one completely.
· After completing lapping, wipe off compound and
then clean the parts.
4st 4/5/6 2020
1 1
2 2
a
5
5-39
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