Yamaha F150B, Service Manual

Page: 268 / 458

7-55
Power unit
POWR
Checking the piston ring groove
1. Measure the piston ring grooves.
Replace the piston and connecting rod
assembly if out of specification.
Checking the piston ring side
clearance
1. Measure the piston ring side clearance.
Replace the piston and connecting rod
assembly, piston ring set if out of specifi-
cation.
Checking the connecting rod big end
side clearance
1. Measure the connecting rod big end side
clearance
a
.
Checking the crankshaft
1. Measure the crankshaft journal diameter
a
, crankpin diameter
b
, and crankpin
width
c
. Replace the crankshaft if out of
specification.
Piston ring end gap
a
:
Top ring:
0.15–0.30 mm (0.0059–0.0118 in)
Second ring:
0.30–0.45 mm (0.0118–0.0177 in)
Oil ring:
0.15–0.60 mm (0.0059–0.0236 in)
Measuring point
b
:
20 mm (0.8 in)
Piston ring groove:
Top ring
a
:
1.23–1.25 mm (0.0484–0.0492 in)
Second 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)
a
b
c
a
b
c
Piston ring side clearance:
Top ring
a
:
0.04–0.08 mm (0.0016–0.0031 in)
Second 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)
Connecting rod big end
side clearance
a
(reference data):
0.14–0.31 mm (0.006–0.012 in)
a
a