Crankshaft; Bearings And Oil Seals; Crankcase - Yamaha YT175J 1982 Service Manual

Crankshaft
1. The crankshaft requires the highest
degree of accuracy in engineering and
servicing of all the engine parts.
2. The crankshaft is susceptible to wear
and therefore the crank bearings must
be inspected with special care.
3. Check crankshaft components by the
charts.
Check connecting rod axial play at small
end (to determine the amount of wear of
crank pin and bearing at large end).
F
-
o
Crankshaft specifications
Crank width (A)
56-{)·05 mm (2.2-{)·002 in)
-{).10
-{).004
Runout limit (C)
0.03 mm (0.012 in)
Connecting rod big end 0.2-0.7mm
side clearance
(0)
(0.008 - 0.03 in)
Small end free play limit 0.4-2.0mm
(F)
(0.016 - 0.08 in)
Bearings and oil seals
1. After cleaning and lubricating bearings,
rotate inner race with a finger. If rough
spots are noticed, replace the bearing.
NOTE: ____________________ __
Bearing(s) are most easily removed or in-
stalled if the cases are first heated to approx-
imately 90° - 120°C (194° - 248°F). Bring
the case up to proper temperature slowly.
Use an oven.
2. Check oil seal lips for damage wear.
Replace as required.
3. Always replace crankshaft oil seals
whenever the crankshaft is removed.
4. Installation
In!?tall bearing(s) and oil seal(s) with
their manufacture marks or numbers
facing outward (That is, you can see its
marks or numbers easily.).
3-15
Crankcase
1. Visually inspect case halves for any
cracks, damage etc.
2. If .bearing(s) have been removed, check
their seats for signs of damage (such as
the bearing spinning in the seat, etc.).
3. Check oil delivery passages in transfer
ports for signs of blockage.
4. If bearings have not been removed, oil
them thoroughly immediately after
washing and drying. Rotate the bear-
ings, checking for roughness indicating
damaged races or balls.
5. Check needle bearing(s) in transmission
section for damage. Replace as re-
quired.