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 F225F Service Manual

POWR
Piston ring dimension:
Top ring a:
B: 1.200 mm (0.0472 in)
T: 2.800–3.000 mm (0.1102–0.1181 in)
2nd ring b:
B: 1.170–1.190 mm (0.0461–0.0469 in)
T: 3.800–4.000 mm (0.1496–0.1575 in)
Oil ring c:
B: 2.400–2.470 mm (0.0945–0.0972 in)
T: 2.350–2.750 mm (0.0925–0.1083 in)

Checking the piston ring end gap

1. Level the piston ring a in the cylinder
using a piston crown at the specified
measuring point a.
2. Measure the piston ring end gap b.
a
a
b
Measuring point a (reference data):
20.0 mm (0.8 in)
Piston ring end gap b (reference data):
Top ring:
0.200–0.300 mm (0.0079–0.0118 in)
2nd ring:
0.600–0.750 mm (0.0236–0.0295 in)
Oil ring:
0.150–0.600 mm (0.0059–0.0236 in)

Checking the piston ring groove

1. Measure the
Replace the piston if out of specification.
7-79
Power unit
piston ring grooves.
Piston ring groove:
Top ring a:
1.230–1.250 mm (0.0484–0.0492 in)
2nd ring b:
1.220–1.240 mm (0.0480–0.0488 in)
Oil ring c:
2.510–2.530 mm (0.0988–0.0996 in)
Checking the piston ring side
clearance
1. Measure the piston ring side clearance.
Piston ring side clearance:
Top ring a:
0.030–0.050 mm (0.0012–0.0020 in)
2nd ring b:
0.030–0.070 mm (0.0012–0.0028 in)
Oil ring c:
0.040–0.130 mm (0.0016–0.0051 in)
Checking the piston pin boss inside
diameter
1. Measure the piston pin boss inside diam-
eter.
a
b
c
a
b
c