SELVA MARINE Blue Whale 250 EFI, Service Manual

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6P23H11
5-48
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b
Previous contact width
8. If the valve seat contact area is too nar-
row and situated near the bottom edge of
the valve face, use a 60
° cutter to cut the
bottom edge of the valve seat. If neces-
sary, use a 45
° cutter to center the area
and set its width.
b
Previous contact width
9. Apply a thin, even layer of lapping com-
pound onto the valve seat, and then lap
the valve using a valve lapper (commer-
cially available).
CAUTION:
Do not get the lapping compound on the
valve stem and valve guide.
10. After every lapping procedure, be sure to
clean off any remaining lapping com-
pound from the cylinder heads and the
valves.
11. Check the valve seat contact area of the
valve again.
Checking the cylinder head
1. Eliminate carbon deposits from the com-
bustion chambers and check for deterio-
ration.
2. Check the cylinder head warpage using a
straightedge
1
and thickness gauge
2
in the directions shown. Replace the cyl-
inder head assembly if above specifica-
tion.
Cylinder head warpage limit:
0.1 mm (0.0039 in)
Cylinder head