Yamaha F90D - Checking the Cylinder Head

6D81G11
5-32
1
2
3
4
5
6
7
8
9
2. Measure the camshaft runout. Replace if
above specification.
3. Measure the camshaft journal diameter
c
and cylinder head journal inside diam-
eter
d
. Replace the camshaft and cylin-
der head if out of specification.
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 if above
specification.
Cam lobe
a
:
Intake:
36.48–36.58 mm
(1.4362–1.4402 in)
Exhaust:
36.90–37.06 mm
(1.4528–1.4591 in)
Cam lobe
b
:
Intake:
29.95–30.05 mm
(1.1791–1.1831 in)
Exhaust:
29.92–30.08 mm
(1.1780–1.1842 in)
Camshaft runout limit:
0.03 mm (0.0012 in)
S6D85450
Camshaft journal diameter
c
:
24.960–24.980 mm
(0.9827–0.9835 in)
Camshaft cap inside diameter
d
:
25.000–25.021 mm
(0.9843–0.9851 in)
Cylinder head warpage limit:
0.1 mm (0.0039 in)
S69J5970
d
c
S6D85470
1
2
S6D85460
Cylinder head