Checking The Piston Diameter; Checking The Cylinder Bore; Checking The Piston Clearance (Reference); Checking The Piston Ring - SELVA MARINE Blue Whale 250 EFI Service Manual

NOTE:
Be sure to keep the bearings in the order as
they were removed.

Checking the piston diameter

1. Measure the piston outside diameter at
the specified measuring point. Replace
the piston if out of specification.
Piston diameter a:
93.921–93.941 mm
(3.6977–3.6985 in)
Measuring point b:
5.0 mm (0.2 in) up from the bottom
of the piston skirt

Checking the cylinder bore

1. Measure the cylinder bore (D
measuring points a, b, and c, and in
direction d (D
, D
1 3
to the crankshaft, and direction e (D
D , D ), which is at a right angle to the
4 6
crankshaft.
a
D
b
2
c
D
4
D
6
a 20 mm (0.8 in)
b 50 mm (2.0 in)
c 80 mm (3.1 in)
6P23H11
–D ) at
1 6
, D ), which is parallel
5
,
2
D
1
d
D
3 e
D
5
S69J5B70
Cylinder bore (D
94.000–94.017 mm
(3.7008–3.7014 in)
Checking the piston clearance
(reference)
1. Check the clearances by referring to the
specified values if replacing the piston,
the piston rings as a set, the cylinder
block, or all parts.
Piston clearance (reference data):
0.075–0.080 mm
(0.0030–0.0031 in)

Checking the piston ring

1. Check the piston ring dimensions of B
and T. Replace the piston ring set if out
of specification.
Piston ring dimensions:
Top ring a:
B: 1.17–1.19 mm
(0.046–0.047 in)
T: 2.80–3.00 mm
(0.110–0.118 in)
Second ring b:
B: 1.17–1.19 mm
(0.046–0.047 in)
T: 3.70–3.90 mm
(0.146–0.154 in)
Oil ring c:
B: 2.40–2.47 mm
(0.094–0.097 in)
T: 2.30–2.70 mm
(0.091–0.106 in)
Cylinder block
–D ):
1 6
5-58
1
2
3
4
5
6
7
8
9