Yamaha F40BED, Service Manual

Page: 252 / 537

CRANKSHAFT AND PISTON
5-42
E
POWR
CHECKING THE PISTON-TO-
CYLINDER CLEARANCE
1. Measure:
• Cylinder bore
Out of specification
→
Rebore the
cylinder or replace the cylinder
block.
NOTE:
Measure the cylinder bore in parallel and at
a right angle to the crankshaft. Then, aver-
age the measurements.
2. Measure:
• Piston diameter
Out of specification
→
Replace the
piston.
D
1
D
1
and D
2
D
3
and D
4
D
5
and D
6
D
2
D
60mm (2.4in)
40mm (1.6in)
20mm (0.8in)
Standard
Wear
limit
Cylinder
bore "D" 65.000 - 65.015 mm
(2.5590 - 2.5596 in)
—
Taper limit
"T"
—
0.08 mm
(0.003 in)
Out of
round limit
—
0.08 mm
(0.003 in)
D = Maximum Dia. (D
1
- D
6
)
T = (maximum D
1
or D
2
)-(minimum D
5
or D
6
)
a
Distance
Piston diameter
Standard
2 mm
(0.07 in)
64.950 - 64.965 mm
(2.5570 - 2.5573 in)
Oversize piston diameter
Oversize 1
+ 0.25 mm (0.001 in)
Oversize 2
+ 0.50 mm (0.002 in)
a