Yamaha LB50IIAC - Yamaha Crankshaft Inspection

Crankshaft
1. The crankshaft requires the highest
degree of accuracy in engineering and
servicing
of all the engine parts.
2. The
crankshaft is more susceptible to
wear, and therefore, the crank bearings
must be inspected with special care.
3. Check
crankshaft components per chart.
Checking side clearance
@~lHI-~
1. Axial play
Checking crankshaft runout
2. Side clearance
Check connecting rod axial play
Small end play should not exceed
If small end play exceeds 2
mm,
at small
end (to determine the
2.0 mm.
disassemble the crankshaft, check
amount of wear of crank pin and
connecting rod, crank pin and big
bearing at big end).
end
bearing.
Replace
defective
parts.
Play after
reassembly
should be within 0.8 ~ 1.0 mm.
Check the
connecting
rod side
Move the connecting rod to one
If excessive side clearance play is
clearance at big end.
side and insert a feeler gauge.
present,
0.6 mm or motor disas-
Big end
side clearance play should
semble the crankshaft and replace
be
within 0.2 ~ 0.5 mm.
any worn parts.
Check
crankshaft
assembly
Dia!
gauge
readings
should
be
Correct any misalignment by tap-
runout.
(Misalignment of
within 0.02 mm.
ping the flywheel with a
brass
crankshaft parts)
hammer and by using a wedge.
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