Checking The Piston Ring End Gap; Checking The Piston Ring Groove; Checking The Piston Ring Side Clearance; Checking The Piston Pin Boss Inside Diameter - Yamaha F150A Service Manual

Checking the piston ring end gap

1. Level the piston ring "1" in the cylinder
using a piston crown at the specified
measuring point "a".
2. Measure the piston ring end gap "b".
a
b
Measuring point "a": 10.0 mm (0.39 in)
Piston ring end gap "b" (reference data):
Top ring:
0.20–0.30 mm (0.0079–0.0118 in)
2nd ring:
0.30–0.45 mm (0.0118–0.0177 in)
Oil ring:
0.15–0.60 mm (0.0059–0.0236 in)

Checking the piston ring groove

1. Measure the piston ring grooves.
Piston ring groove:
Top ring "a":
1.23–1.25 mm (0.0484–0.0492 in)
2nd ring "b":
1.22–1.24 mm (0.0480–0.0488 in)
Oil ring "c":
2.51–2.53 mm (0.0988–0.0996 in)
Checking the piston ring side
clearance
1. Measure the piston ring side clearance.
1
Checking the piston pin boss inside
diameter
1. Measure the piston pin boss inside diam-
When measuring the piston pin boss inside
diameter, do not measure it at the ring groove
"b" or oil groove "c".
a
b
c
7-65
Piston ring side clearance:
Top ring "a":
0.04–0.08 mm (0.0016–0.0031 in)
2nd ring "b":
0.03–0.07 mm (0.0012–0.0028 in)
Oil ring "c":
0.04–0.13 mm (0.0016–0.0051 in)
eter "a".
TIP:
a
Piston pin boss inside diameter "a":
21.021–21.031 mm
(0.8276–0.8280 in)
Crankcase
a
b
c
b
c
c
0
1
2
3
4
5
6
7
8
9
10
A