Yamaha YZ450F(Y Owner's Manual page 65

Standard position:
12 clicks out
* 10 clicks out
* Except for USA and CDN
Do not force the adjuster past the
minimum or maximum extent of
adjustment. The adjuster may be
damaged.
Always adjust each front fork to
the same setting. Uneven adjust-
ment can cause poor handling and
loss of stability.
CHECKING THE REAR SHOCK
ABSORBER
1. Inspect:
• Swingarm smooth action
Abnormal noise/unsmooth action
→ Grease the pivoting points or
repair the pivoting points.
Damage/oil leakage → Replace.
ADJUSTING THE REAR SHOCK
ABSORBER SPRING PRELOAD
1. Elevate the rear wheel by placing
the suitable stand under the en-
gine.
2. Remove:
• Rear frame
3. Measure:
• Spring fitting length
Standard fitting length:
I.D. MARK/
Length
Q'TY
Pink/1 266 mm
(10.47 in)
*263 mm
(10.35 in)
Pink/2 272 mm
(10.71 in)
*269 mm
(10.59 in)
Pink/3 263.5 mm
(10.37 in)
*260.5 mm
(10.26 in)
* Except for USA and CDN
• The I.D. mark "a" is marked at the
end of the spring.
• Spring specification varies accord-
ing to the difference in the produc-
tion lot.
4. Adjust:
• Spring preload
Adjustment steps:
a. Loosen the locknut "1".
b. Loosen the adjuster "2" until there
is some clearance between the
spring and adjuster.
c. Measure the spring free length
"a".
d. Turn the adjuster "2".
Stiffer → Increase the spring pre-
load. (Turn the adjuster "2" in.)
Softer → Decrease the spring pre-
load. (Turn the adjuster "2"
out.)
Extent of adjustment:
Maximum Minimum
Position in Position in
which the which the
spring is turned spring is turned
in 13 mm (0.51 in 1.5 mm (0.06
in) from its free in) from its free
length. length.
3-19
CHASSIS
Be sure to remove all dirt and mud
from around the locknut and adjust-
er before adjustment.
• The length of the spring (installed)
changes 1.5 mm (0.06 in) per turn
of the adjuster.
Never attempt to turn the adjuster
beyond the maximum or minimum
setting.
e. Tighten the locknut.
Locknut:
30 Nm (3.0 m•kg, 22
ft•lb)
5. Install:
• Rear frame (upper)
Rear frame (upper):
38 Nm (3.8 m•kg, 27
ft•lb)
• Rear frame (lower)
Rear frame (lower):
32 Nm (3.2 m•kg, 23
ft•lb)
ADJUSTING THE REAR SHOCK
ABSORBER REBOUND DAMPING
FORCE
1. Adjust:
• Rebound damping force
By turning the adjuster "1".
Stiffer "a" → Increase the re-
bound damping force. (Turn
the adjuster "1" in.)
Softer "b" → Decrease the re-
bound damping force. (Turn
the adjuster "1" out.)
Extent of adjustment:
Maximum Minimum
20 clicks out
Fully turned in
(from maximum
position
position)