Checking The Piston Ring End Gap; Checking The Piston Ring Groove - Yamaha F30A Service Manual

Piston ring dimensions:
Top ring a:
B: 1.17–1.19 mm
(0.0461–0.0469 in)
T: 2.30–2.50 mm
(0.0906–0.0984 in)
2nd ring b:
B: 1.47–1.49 mm
(0.0579–0.0587 in)
T: 2.60–2.80 mm
(0.1024–0.1102 in)
Oil ring c:
B: 2.36–2.48 mm
(0.0929–0.0976 in)
T: 2.75 mm (0.1083 in)
(reference data)

Checking the piston ring end gap

1. Level the piston ring 1 in the cylinder
with a piston crown at the specified mea-
suring point a.
2. Measure the piston ring end gap b.
a
NOTE:
The figures are for reference only. Depend-
ing on how the parts are assembled, the
actual measurements may not be within the
specified ranges.
67C3K11
1
b
S67C5129
Piston ring end gap b (reference
data):
Top ring:
0.15–0.30 mm
(0.0059–0.0118 in)
2nd ring:
0.30–0.50 mm
(0.0118–0.0197 in)
Oil ring:
0.20–0.70 mm
(0.0079–0.0276 in)
Measuring point a (reference data):
20 mm (0.8 in)

Checking the piston ring groove

1. Measure the piston
Replace the piston if out of specification.
Piston ring groove:
Top ring a:
1.21–1.23 mm
(0.0476–0.0484 in)
2nd ring b:
1.51–1.53 mm
(0.0594–0.0602 in)
Oil ring c:
2.52–2.54 mm
(0.0992–0.1000 in)
Cylinder block
1
2
3
ring grooves.
4
a
b
5
c
S67C5130
6
7
8
9
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