Crankshaft; Bearing And Oil Seals; Crankcase; Engine Assembling And Adjustment - Yamaha QT 50F Service Manual

2. Check pinion teeth for damage or
scratches. If teeth are excessively
damaged or scratched, replace the
pinion.
i
J. Crankshaft
1. The crankshaft requires the highest
degree of accuracy in engineering and
servicing ojf 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. j
Check connecting rod axial play at small
end (to determine the amount of wear
of crank pin and bearing at large end).
Crankshaft specifications
I
I
Deflection tolerande (A)
Left side
0.03
(0.0012)
Right side
0I03
(0.d,012)
Unit: mm (in)
Flywheel width (B)
38_oo5
(1.50_o.002)
I Unit: mm (in)
Rod Clearance
Axial (C
New
0.4 ~ 0.8
(0.016 ~ 0.031)
) 1
Majc.
2.0|
(o.od)
Side (D)
Min.
0.35
(0.014)
Max.
0.55
(0.021)
NOTE:
Bearing(s) are most easily removed or
installed if the cases are first heated to ap-
proximately 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
Install bearing(s) and oil seal(s) with
their manufacture marks or numbers
facing outward (That is, you can see its
marks or numbers easily.).
L Crankcase
1. Visually inspect case halves for any
cranks, 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.
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K. Bearings and Oil Seals
1. After cleaning ar|d lubricating bearings,
rotate inner race jwith a finger. If rough
spots are noticed,) replace the bearing.
3-4. ENGINE ASSEMBLING
JUSTMENT
AND AD
A. Crankshaft Installation
After all bearings and seals have been in-
stalled in both crankcase halves, install
crankshaft as follows:
3-10