Service Points; Cylinder Head Inspection - Yamaha 40V Service Manual

POWR
CYLINDER HEAD, THERMOSTAT AND EXHAUST
COVER

SERVICE POINTS

Cylinder head inspection

1. Inspect:
Water jacket
Material deposit/Corrosion → Clean.
Cylinder inner surface
Score marks → Clean.
Use #600 ~ 800 grit wet sandpaper.
CAUTION:
Do not scratch the fitting surfaces of the
cylinder and cylinder cover.
2. Measure:
Cylinder head warpage
Use a straightedge and thickness
gauge.
Out of specification → Resurface or
replace.
Warpage limit:
0.1 mm (0.004 in)
Resurfacing steps:
Place a 400 ~ 600 grit wet sandpaper
on the surface plate.
Resurface the head using a figure-
eight sanding pattern.
NOTE:
Rotate the head several times to avoid
removing too much material from one
side.
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