SELVA MARINE Blue Whale 250 EFI, Service Manual

Page: 172 / 377

POWR
Power unit
5-59
6P23H11
Checking the piston ring end gap
(reference)
1. Level the piston ring
1
in the cylinder
with a piston crown.
2. Check the piston ring end gap
a
at the
specified measuring point
b
.
Checking the piston ring groove
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 piston pin boss bore
1. Measure the piston pin boss bore.
Replace the piston if out of specification.
Piston ring end gap
a
(reference data):
Top ring:
0.15 – 0.30 mm (0.006 – 0.012 in)
Second ring:
0.30 – 0.45 mm (0.012 – 0.018 in)
Oil ring:
0.15 – 0.60 mm (0.006 – 0.024 in)
Measuring point
b
(reference data):
20 mm (0.8 in)
Piston ring groove:
Top ring
a
:
1.23 – 1.25 mm (0.048 – 0.049 in)
Second ring
b
:
1.22 – 1.24 mm (0.048 – 0.049 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 (0.002 – 0.003 in)
Second ring
b
:
0.03 – 0.07 mm (0.001 – 0.003 in)
Oil ring
c
:
0.04 – 0.13 mm (0.002 – 0.005 in)