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3.2.6. Crank shaft
1) Inspection for scores or cracks
(1) Visually check the crank shaft journal and crank pins for scores or cracks.
(2) Using a magnetic power and color check, inspect the crank shaft for cracks, and replace
the crank shaft which has cracks.
2) Checking crank shaft for wear
(1) With an outside micrometer, measure the diameter of the crank shaft journals and pins in
the directions as shown, and compare the measured values to determine the amount of
wear.
(2) If the amount of wear is beyond the limit, have the crank shaft ground and install under-
size bearings. However, if the amount of wear is within the limit, you can correct the wear
using an oil stone or oiled grinding paper of fine grain size.
(Be sure to use grinding paper which has been immersed in oil.)
•
Undersize bearings available
(1) Standard
(2) 0.25 (Inside diameter is 0.25mm
lesser than the standard size.)
(3) 0.50 (Inside diameter is 0.50mm
lesser than the standard size.)
(4) 0.75 (Inside diameter is 0.75mm
lesser than the standard size.)
(5) 1.00 (Inside diameter is 1.00mm
lesser than the standard size.)
Undersize bearings are available in
4 different sizes as indicated above,
and the crankshaft can be reground
to the above sizes.
- 54 -
B
B
B
A
A
B
EFM2047I
<Figure 3-12> Measuring crank shaft outer
diameter
Note : When regrinding the crank
shaft as described above, the
fillet section 'R' should be fin-
ished correctly.
Avoid sharp corners or insuffi-
cient fillet.
Standard values of 'R'
Crankshaft pin 'R' : 4.5
Crankshaft journal 'R' : 4
" R "
" R "
" R "
Right
Wrong
Wrong
" R "
" R "
EFM2048I
<Figure 3-13> The shape of crankshaft 'R'
1
2
“R”