Yamaha F150B, Service Manual

Page: 267 / 458

7-54
Crankcase
0
1
2
3
4
5
6
7
8
9
10
A
Checking the piston diameter
1. Measure the piston outside diameter at
the specified measuring point. Replace if
out of specification.
Checking the cylinder bore
1. Measure the cylinder bore (D
1
–D
6
) at
measuring points
a
,
b
, and
c
, and in
direction
d
(D
1
, D
3
, D
5
), which is parallel
to the crankshaft, and direction
e
(D
2
,
D
4
, D
6
), which is at a right angle to the
crankshaft.
a
20 mm (0.8 in)
b
60 mm (2.4 in)
c
100 mm (3.9 in)
Checking the piston ring
1. Check the piston ring dimensions B and
T. Replace the piston ring set if out of
specification.
Checking the piston ring end gap
(reference)
1. Level the piston ring
a
in the cylinder
with a piston crown.
2. Check the piston ring end gap
a
at the
specified measuring point
b
.
Piston diameter
a
:
93.921–93.941 mm (3.6977–3.6985 in)
Measuring point
b
:
14.0 mm (0.55 in) up from the bottom
of the piston skirt
Cylinder bore (D
1
–D
6
):
94.000–94.017 mm (3.7008–3.7014 in)
a
b
D
1
D
2
D
3
D
4
D
5
D
6
a
b
c
d
e
Piston ring dimensions:
Top ring
a
:
B:1.17–1.19 mm (0.0461–0.0469 in)
T:2.80–3.00 mm (0.1102–0.1181 in)
Second ring
b
:
B:1.17–1.19 mm (0.0461–0.0469 in)
T:3.70–3.90 mm (0.1457–0.1535 in)
Oil ring
c
:
B:2.40–2.47 mm (0.0945–0.0972 in)
T:2.30–2.70 mm (0.0906–0.1063 in)
T
B
T
T
B
B
a b
c
a
a
b