Yamaha F150A - Checking the Piston Diameter; Checking the Cylinder Bore; Checking the Piston Ring

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Crankcase
6. Remove the clips “1” and piston pin “2”,
and then remove the connecting rod “3”.
TIP:
Make sure to keep the parts in the order of
removal.
Checking the piston diameter
1. Measure the piston outside diameter “a”
at the specified measuring point “b”.
Checking the cylinder bore
1. Measure the cylinder bore (D1–D6) at
measuring points “a”, “b”, and “c”, and in
directions “d” (D
1, D3, D5) and “e” (D2, D4,
D
6).
a. 10.0 mm (0.39 in)
b. 50.0 mm (1.97 in)
c. 85.0 mm (3.35 in)
d. Parallel to the crankshaft
e. At a right angle to the crankshaft
Checking the piston ring
1. Measure piston ring dimensions B and T.
Bearing separator “2”: 90890-06534
Gear puller “3”: 90890-06540
General cylindrical tool “4”:
a = 19.9 mm (0.78 in)
b = 90.0 mm (3.54 in)
Piston diameter “a”:
93.921–93.941 mm
(3.6977–3.6985 in)
Measuring point “b”:
13.5 mm (0.53 in) above the bottom of
the piston skirt
1
1
2
3
a
b
Cylinder bore (D1–D6):
94.000–94.017 mm
(3.7008–3.7014 in)
Piston ring dimensions:
Top ring “a”:
B: 1.170–1.185 mm (0.0461–0.0467 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: 3.700–3.900 mm (0.1457–0.1535 in)
Oil ring “c”:
B: 2.400–2.470 mm (0.0945–0.0972 in)
T: 2.300–2.700 mm (0.0906–0.1063 in)
a
b
c
d
e
D
1
D
2
D
3
D
4
D
5
D
6
c
b
a
B
T
T
B
T
B