Yamaha F80B, Service Manual

Page: 112 / 249

POWR
Power unit
5-43
6D93G11
3. Check the piston ring end gap
d
at the
specified measuring point. Replace if out
of specification.
Checking the piston ring grooves
1. Measure the piston ring grooves.
Replace the piston if out of specification.
Checking the piston ring side
clearance
1. Measure the piston ring side clearance.
Replace the piston and piston rings as a
set if out of specification.
Checking the connecting rod big end
side clearance
1. Measure the connecting rod big end side
clearance
a
. Replace the connecting
rod or crankshaft or both if out of specifi-
cation.
Piston ring end gap
d
:
Top ring:
0.15–0.30 mm
(0.0059–0.0118 in)
Second ring:
0.70–0.90 mm
(0.0276–0.0354 in)
Oil ring:
0.20–0.70 mm
(0.0079–0.0276 in)
Measuring point
e
: 20 mm (0.8 in)
S63P5720
a
b
c
Piston ring groove:
Top ring
a
:
1.23–1.25 mm (0.048–0.049 in)
Second ring
b
:
1.52–1.54 mm (0.060–0.061 in)
Oil ring
c
:
2.51–2.53 mm (0.099–0.100 in)
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
:
0.03–0.15 mm
(0.0012–0.0059 in)
S63P5730
a
b
c