Yamaha YZ450F(Y Owner's Manual page 101

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.
Clutch holding tool:
YM-91042/90890-04086
A. For USA and CDN
B. Except for USA and CDN
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:
50.0 mm (1.97 in)
<Limit>: 49.0 mm (1.93
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:
2.92–3.08 mm (0.115–
0.121 in)
<Limit>: 2.8 mm (0.110
in)
CHECKING THE CLUTCH PLATES
1. Measure:
• Clutch plate warpage
Out of specification → Replace
clutch plate as a set.
Use a surface plate "1" and thick-
ness gauge "2".
Warp limit:
0.1 mm (0.004 in)
4-31
CLUTCH
CHECKING THE PUSH LEVER
SHAFT
1. Inspect:
• Push lever shaft "1"
Wear/damage → Replace.
CHECKING THE PUSH ROD
1. Inspect:
• Push rod 1 "1"
• Bearing "2"
• Washer "3"
• Push rod 2 "4"
• Ball "5"
Wear/damage/bend → Replace.
INSTALLING THE PUSH LEVER
SHAFT
1. Install:
• Push lever shaft "1"
• Apply the lithium soap base grease
on the oil seal lip.
• Apply the engine oil on the push le-
ver shaft.
INSTALLING THE CLUTCH
1. Install:
• Primary driven gear "1"
• Thrust washer "2"
• Clutch boss "3"
Apply the engine oil on the primary
driven gear inner circumference.