Yamaha YZ125 2019 Owner's Service Manual page 145

CHECKING THE CRANKCASE
1. Inspect:
• Contacting surface "a"
Scratches → Replace.
• Engine mounting boss "b", crankcase
Cracks/damage → Replace.
2. Inspect:
• Bearing "1"
Rotate inner race with a finger.
Rough spot/seizure → Replace.
CRANKCASE AND CRANKSHAFT
3. Inspect:
• Oil seal "1"
Damage → Replace.
CHECKING THE CRANKSHAFT
1. Measure:
• Runout limit "a"
• Small end free play limit "b"
• Connecting rod big end side clearance "c"
• Crank width "d"
Out of specification → Replace.
Use the dial gauge and a thickness gauge.
Dial gauge & stand set:
YU-03097-B/90890-01252
Runout lim- 0.030 mm (0.0012
it:
Small end
free play:
Side clear- 0.060–0.640 mm
ance: (0.0024–0.0252 in)
Crack 55.90–55.95 mm
width: (2.201–2.203 in)
4-58
Standard <Limit>
0.050
mm
in) (0.0020
in)
0.80–1.00 mm 2.0 mm
(0.03–0.04 in) (0.08 in)
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