TOHATSU BFT 250A, Service Manual

Page: 451 / 639

15-37
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CYLINDER BLOCK
Select the correct bearing by referring to the cylinder
block I.D. code letter or number and the crankshaft
main journal code number.
Crankshaft main bearing selection table
Main bearing identification table
Main bearing center thickness: 2.5 mm (0.10 in)
When using bearing halves of different colors, it does
not matter which color is used in the top or bottom.
Each rod falls into one of six tolerance ranges (from -
0.009 mm (-0.0004 in) to 0.015 mm (0.0006 in)), in
0.004 mm (0.0002 in).
Note that the bearings are selected so that the oil
clearance is in the range between 0.020 – 0.046 mm
(0.0008 – 0.0018 in.)
After installing the selected bearing(s), measure the oil
clearance (page 15-34).
Apply molybdenum disulfide oil to the crankshaft mating
surface. Do not apply to the cylinder block and
crankcase mating surfaces.
Align the bearing tab [1] with the grooves in the
crankcase and cylinder block, and assemble carefully
not to damage the sliding surface.
• Be sure to measure the main bearing oil clearance
after selecting the bearing by referring to the
selection table.
• If the two bearing I.D. colors are shown on the
selection table, use a bearing of the respective
colors.
Crankshaft
main journal
code number
Cylinder block I.D. code number or
letter
A or I B or II C or III D or IIII
Bearing I.D. color
1 or I Pink
Pink/
Yellow
Yellow
Yellow/
Green
2 or II
Pink/
Yellow
Yellow
Yellow/
Green
Green
3 or III Yellow
Yellow/
Green
Green
Green/
Brown
4 or IIII
Yellow/
Green
Green
Green/
Brown
Brown
5 or IIIII Green
Green/
Brown
Brown
Brown/
Black
6 or IIIIII
Green/
Brown
Brown
Brown/
Black
Black
Number I.D. color Tolerance ranges
F Red
–0.009 – –0.005 mm
(–0.0004 – –0.0002 in)
E Pink
–0.005 – –0.001 mm
(–0.0002 – –0.0001 in)
D Yellow
–0.001 – +0.003 mm
(–0.0001 – +0.0001 in)
C Green
+0.003 – +0.007 mm
(+0.0001 – +0.0003 in)
B Brown
+0.007 – +0.011 mm
(+0.0003 – +0.0004 in)
A Black
+0.011 – +0.015 mm
(+0.0004 – +0.0006 in)
IDENTIFICATION COLOR
[1]