Yamaha F90D, Service Manual

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6D81G11
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4. Measure the valve stem runout. Replace
if above specification.
Checking the valve guides
NOTE:
Before checking the valve guide make sure
that the valve stem diameter is within specifi-
cation.
1. Measure the valve guide inside diameter
a
.
2. Calculate the valve stem-to-valve guide
clearance as follows. Replace the valve
guide if out of specification.
Replacing the valve guides
1. Remove the valve guide
1
by striking
the special service tool from the combus-
tion chamber side.
Valve stem diameter
b
:
Intake:
5.975–5.990 mm
(0.2352–0.2358 in)
Exhaust:
5.960–5.975 mm
(0.2346–0.2352 in)
Valve stem runout limit:
0.01 mm (0.0004 in)
Valve guide inside diameter
a
:
Intake and exhaust:
6.000–6.018 mm
(0.2362–0.2369 in)
Valve stem-to-valve guide clearance
= valve guide inside diameter – valve
stem diameter:
Intake:
0.010–0.043 mm
(0.0004–0.0017 in)
Exhaust:
0.025–0.058 mm
(0.0010–0.0023 in)
Valve guide remover/installer:
YM-04064-A
S60C5450
a
Cylinder head