Yamaha YZ125 2019 Owner's Service Manual page 117

REMOVING THE CLUTCH BOSS
1. Remove:
• Nut "1"
• Lock washer "2"
• Clutch boss "3"
Straighten the lock washer tab and use the
clutch holding tool "4" to hold the clutch boss.
Universal clutch holder:
YM-91042/90890-04086
A. For USA and CAN
B. Except for USA and CAN
CHECKING THE CLUTCH HOUSING AND
BOSS
1. Inspect:
• Clutch housing "1"
Cracks/wear/damage → Replace.
• Clutch boss "2"
Scoring/wear/damage → Replace.
CHECKING THE PRIMARY DRIVEN GEAR
1. Check:
• Circumferential play
Free play exists → Replace.
• Gear teeth "a"
Wear/damage → Replace.
CHECKING THE CLUTCH SPRINGS
1. Measure:
• Clutch spring free length "a"
Out of specification → Replace springs as a
set.
Clutch spring free length "a":
40.10 mm (1.58 in)
<Limit>: 38.10 mm (1.50 in)
CHECKING THE FRICTION PLATES
1. Measure:
• Friction plate thickness
Out of specification → Replace friction plate
as a set.
Measure at all four points.
Friction plate thickness:
2.90–3.10 mm (0.114–0.122 in)
<Limit>: 2.80 mm (0.110 in)
4-30
CLUTCH