Yamaha F60A - Cylinder Bore and Piston Ring Groove Inspection

69W3D1X
56
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)
2. Calculate the taper limit. Replace or
rebore the cylinder block if out of specifi-
cation.
3. Calculate the out-of-round limit. Replace
or rebore the cylinder block if out of spec-
ification.
Checking the piston ring grooves
1. Measure the piston ring grooves.
Replace the piston if out of specification.
Cylinder bore (D
1
–D
6
):
65.00–65.01 mm
(2.5591–2.5594 in)
Taper limit:
D
1
–D
5
(direction
d
)
D
2
–D
6
(direction
e
)
0.08 mm (0.0031 in)
Out-of-round limit:
D
2
–D
1
(measuring point
a
)
D
6
–D
5
(measuring point
c
)
0.01 mm (0.0004 in)
S69W5080
D 1 D 2
D 3 D 4
D 5 D 6
Piston ring groove:
Top ring
a
:
1.21–1.23 mm
(0.0476–0.0484 in)
Second ring
b
:
1.51–1.53 mm
(0.0594–0.0602 in)
Oil ring
c
:
2.52–2.54 mm
(0.0992–0.0999 in)
Power unit