2005 YAMAHA YZ450F weight

4 - 63
ENGBALANCER
REMOVAL POINTS
Balancer drive gear and balancer driven
gear
1. Straighten the lock washer tab.
2. Loosen:
Nut (primary drive gear) 1
Nut (balancer) 2
NOTE:
Place an aluminum plate a between the teeth
of the balancer drive gear 3 and driven gear
4.
a 3
14
2
4 3
a
Balancer
1. Remove:
Balancer 1
NOTE:
When removing the balancer shaft, align the
center of the balancer shaft weight a along
the line connecting the centers of the crank-
shaft and balancer shaft.
INSPECTION
Primary drive gear, balancer drive gear and
balancer driven gear
1. Inspect:
Primary drive gear 1
Balancer drive gear 2
Balancer driven gear 3
Wear/damage → Replace.
Balancer
1. Inspect:
Balancer
Cracks/damage → Replace.

4 - 64
ENGBALANCER
ASSEMBLY AND INSTALLATION
Balancer, balancer drive gear and balancer
driven gear
1. Install:
Balancer 1
NOTE:
When installing the balancer shaft, align the
center of the balancer shaft weight a along
the line connecting the centers of the crank-
shaft and balancer shaft.
2. Install:
Balancer driven gear 1
NOTE:
Install the balancer driven gear onto the bal-
ancer while aligning the punch mark a on the
balancer driven gear with the lower spline b
on the balancer end.
3. Install:
Balancer drive gear 1
NOTE:
Align the punched mark a on the balancer
drive gear with the punched mark b on the
balancer driven gear.
Align the punched mark c on the balancer
drive gear with the lower spline d on the
crankshaft.
4. Install:
Lock washer 1
Nut (balancer) 2
Primary drive gear 3
Conical washer 4
Nut (primary drive gear) 5
NOTE:
Apply engine oil to the contact surface and
threaded portion of the nut (primary drive
gear).
Place an aluminum plate a between the
teeth of the balancer drive gear 6 and driven
gear 7.
Install the primary drive gear with its weight
reduction holes b facing the engine.
Install the conical washer with its convex sur-
face c outward.
5. Bend the lock washer tab.
a 6
17
2
T R..50 Nm (5.0 m · kg, 36 ft · lb)
E
7
6a
c b
5
4
3
T R..110 Nm (11.0 m · kg, 80 ft · lb)

7 - 15
TUN
2. Use of stiff spring
Generally a stiff spring gives a stiff riding
feeling. Rebound damping tends to
become weaker, resulting in lack of a
sense of contact with the road surface or in
a vibrating handlebar.
To set a stiff spring:
Change the rebound damping.
Turn in one or two clicks.
Change the compression damping.
Turn out one or two clicks.
ÈCoverage of spring by weight
ÉRider weight
1Soft
2Standard
3Stiff
SETTING

7 - 18
TUNSETTING
EC72G001
Setting of spring after replacement
After replacement, be sure to adjust the spring
to the set length [sunken length 90 ~ 100 mm
(3.5 ~ 3.9 in)] and set it.
1. Use of soft spring
Set the soft spring for less rebound
damping to compensate for its less spring
load. Run with the rebound damping
adjuster one or two clicks on the softer
side and readjust it to suit your prefer-
ence.
2. Use of stiff spring
Set the soft spring for more rebound
damping to compensate for its greater
spring load. Run with the rebound damp-
ing adjuster one or two clicks on the
stiffer side and readjust it to suit your
preference.
*Adjusting the rebound damping will be fol-
lowed more or less by a change in the com-
pression damping. For correction, turn the
low compression damping adjuster on the
softer side.
CAUTION:
When using a rear cushion other than cur-
rently installed, use the one whose overall
length
a does not exceed the standard as
it may result in faulty performance. Never
use one whose overall length is greater
than standard.
ÈCoverage of spring by weight
ÉRider weight
1Soft
2Standard
3Stiff
Length
a of standard shock:
490.5 mm (19.31 in)