Yamaha YZ450F(B) 2012 Owner's Service Manual page 115

REMOVING THE BALANCER
1. Straighten the lock washer tab.
2. Loosen:
• Nut (balancer) "1"
• Nut (primary drive gear) "2"
• Nut (balancer shaft driven gear)
"3"
Place an aluminum plate "a" between
the teeth of the balancer shaft drive
gear "4" and driven gear "5".
CHECKING THE PRIMARY DRIVE
GEAR, BALANCER SHAFT DRIVE
GEAR AND BALANCER SHAFT
DRIVEN GEAR
1. Inspect:
• Primary drive gear "1"
• Balancer shaft drive gear "2"
• Balancer shaft driven gear "3"
Wear/damage → Replace.
CHECKING THE BALANCER
1. Inspect:
• Balancer
Cracks/damage → Replace.
INSTALLING THE BALANCER
1. Install:
• Balancer shaft driven gear "1"
Install the balancer shaft driven gear
and balancer shaft with their lower
splines "a" aligning with each other.
2. Install:
• Balancer shaft driven gear "1"
• Align the punched mark "a" on the
balancer shaft drive gear with the
punched mark "b" on the balancer
shaft driven gear.
• Install the balancer shaft driven
gear and crankshaft with the lower
splines "c" aligning with each other.
3. Install:
• Lock washer "1"
• Nut (balancer shaft driven gear)
"2"
Nut (balancer shaft driv-
en gear):
50 Nm (5.0 m•kg, 36
ft•lb)
4-34
BALANCER
• Primary drive gear "3"
• Conical washer "4"
• Nut (primary drive gear) "5"
Nut (primary drive gear):
100 Nm (10.0 m•kg, 72
ft•lb)
• Straight key "6"
• Balancer "7"
• Lock washer "8"
• Nut (balancer) "9"
Nut (balancer):
45 Nm (4.5 m•kg, 33
ft•lb)
• Apply molybdenum disulfide grease
to the contact surface and threaded
portion of the nut (primary drive
gear).
• Apply molybdenum disulfide grease
to the contact surface of the conical
spring washer.
• Place an aluminum plate "a" be-
tween the teeth of the balancer
shaft drive gear "10" and balancer
shaft driven gear "11".
• Install the conical washer with its
convex surface "b" outward.
4. Bend the lock washer tab.