2003 YAMAHA YZ450F length

7 - 17
TUNSETTING
NOTE:
If the machine is new and after it is broken in,
the same set length of the spring may
change because of the initial fatigue, etc. of
the spring. Therefore, be sure to make re-
evaluation.
If the standard figure cannot be achieved by
adjusting the spring adjuster and changing
the spring set length, replace the spring with
an optional one and make re-adjustment.
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 preference.
2. Use of stiff spring
Set the soft spring for more rebound
damping to compensate for its greater
spring load. Run with the rebound
damping adjuster one or two clicks on
the stiffer side and readjust it to suit
your preference.
*Adjusting the rebound damping will be
followed more or less by a change in the
compression damping. For correction,
turn the low compression damping
adjuster on the softer side.

7 - 18
TUN
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.
ÅCoverage of spring by weight
ıRider weight
1Soft
2Standard
3Stiff
Length a of standard shock:
490.5 mm (19.31 in)
SETTING

7 - 19
TUNSETTING
EC72Q000
Rear shock absorber setting parts
Rear shock spring 1
[Equal pitch spring]
[Unequal pitch spring]
*For EUROPE
NOTE:
The unequal pitch spring is softer in initial
characteristic than the equal pitch spring and
is difficult to bottom out under full compres-
sion.
The I.D. color a is marked at the end of the
spring.
Extent of adjustment (spring length)
TYPESPRING
RATESPRING
PART NUMBERI.D.
COLOR/
POINTSPRING
FREE
LENGTH
SOFT4.3
4.5
4.7
4.9
5.15UN-22212-00
5UN-22212-10
5UN-22212-20
5UN-22212-30
5UN-22212-40Brown/1
Green/1
Red/1
Black/1
Blue/1260
260
260
260
260
STD 5.3 5UN-22212-50 Yellow/1 260
STIFF5.5
5.75UN-22212-60
5UN-22212-70Pink/1
White/1260
260
TYPESPRING
RATE
(approx.)SPRING
PART NUMBERI.D.
COLOR/
POINTSPRING
FREE
LENGTH
SOFT4.5
4.7
4.9
5.15UN-22212-A0
5UN-22212-B0
5UN-22212-C0
5UN-22212-D0Green/2
Red/2
Black/2
Blue/2275
275
275
275
*STD 5.3 5UN-22212-E0 Yellow/2 275
STIFF5.5
5.75UN-22212-F0
5UN-22212-G0Pink/2
White/2275
275
SPRING FREE
LENGTHEXTENT OF
ADJUSTMENT b
260 mm (10.24 in)240.5 ~ 258.5 mm
(9.47 ~ 10.18 in)
275 mm (10.83 in)255.5 ~ 273.5 mm
(10.06 ~ 10.77 in)

7 - 20
TUNSETTING
EC72H002
Suspension setting
Front fork
NOTE:
If any of the following symptoms is experienced with the standard position as the base, make
resetting by reference to the adjustment procedure given in the same chart.
Before any change, set the rear shock absorber sunken length to the standard figure 90 ~
100 mm (3.5 ~ 3.9 in).
SymptomSection
Check Adjust
JumpLarge
gapMedium
gapSmall
gap
Stiff over entire range

Compression damping
Oil level (oil amount)
SpringTurn adjuster counterclockwise (about 2 clicks) to
decrease damping.
Decrease oil level by about 5 ~ 10 mm (0.2 ~ 0.4 in).
Replace with soft spring.
Unsmooth movement
over entire range

Outer tube
Inner tube
Under bracket tightening
torqueCheck for any bends, dents, and other noticeable
scars, etc. If any, replace affected parts.
Retighten to specified torque.
Poor initial
movement

Rebound damping
Oil sealTurn adjuster counterclockwise (about 2 clicks) to
decrease damping.
Apply grease in oil seal wall.
Soft over entire range,
bottoming out

Compression damping
Oil level (oil amount)
SpringTurn adjuster clockwise (about 2 clicks) to increase
damping.
Increase oil level by about 5 ~ 10 mm (0.2 ~ 0.4 in).
Replace with stiff spring.
Stiff toward stroke end
Oil level (oil amount) Decrease oil level by about 5 mm (0.2 in).
Soft toward stroke end,
bottoming out
Oil level (oil amount) Increase oil level by about 5 mm (0.2 in).
Stiff initial movement
Compression dampingTurn adjuster counterclockwise (about 2 clicks) to
decrease damping.
Low front, tending to
lower front posture

Compression damping
Rebound damping
Balance with rear end
Oil level (oil amount)Turn adjuster clockwise (about 2 clicks) to increase
damping.
Turn adjuster counterclockwise (about 2 clicks) to
decrease damping.
Set sunken length for 95 ~ 100 mm (3.7 ~ 3.9 in) when
one passenger is astride seat (lower rear posture).
Increase oil level by about 5 mm (0.2 in).
“Obtrusive” front, tend-
ing to upper front pos-
ture

Compression damping
Balance with rear end
Spring
Oil lever (oil amount)Turn adjuster counterclockwise (about 2 clicks) to
decrease damping.
Set sunken length for 90 ~ 95 mm (3.5 ~ 3.7 in) when
one passenger is astride seat (upper rear posture).
Replace with soft spring.
Decrease oil level by about 5 ~ 10 mm (0.2 ~ 0.4 in).

7 - 21
TUNSETTING
Rear shock absorber
NOTE:
If any of the following symptoms is experienced with the standard position as the base, make
resetting by reference to the adjustment procedure given in the same chart.
Adjust the rebound damping in 2-click increments or decrements.
Adjust the low compression damping in 1-click increments or decrements.
Adjust the high compression damping in 1/6 turn increments or decrements.
SymptomSection
Check Adjust
JumpLarge
gapMedium
gapSmall
gap
Stiff, tending to sink

Rebound damping
Spring set lengthTurn adjuster counterclockwise (about 2 clicks) to
decrease damping.
Set sunken length for 90 ~ 100 mm (3.5 ~ 3.9 in) when
one passenger is astride seat.
Spongy and unstable

Rebound damping
Low compression damping
SpringTurn adjuster clockwise (about 2 clicks) to increase
damping.
Turn adjuster clockwise (about 1 click) to increase
damping.
Replace with stiff spring.
Heavy and dragging

Rebound damping
SpringTurn adjuster counterclockwise (about 2 clicks) to
decrease damping.
Replace with soft spring.
Poor road gripping

Rebound damping
Low compression damping
High compression damp-
ing
Spring set length
SpringTurn adjuster counterclockwise (about 2 clicks) to
decrease damping.
Turn adjuster clockwise (about 1 clicks) to increase
damping.
Turn adjuster clockwise (about 1/6 clicks) to increase
damping.
Set sunken length for 90 ~ 100 mm (3.5 ~ 3.9 in) when
one passenger is astride seat.
Replace with soft spring.
Bottoming out

High compression damp-
ing
Spring set length
SpringTurn adjuster clockwise (about 1/6 turn) to increase
damping.
Set sunken length for 90 ~ 100 mm (3.5 ~ 3.9 in) when
one passenger in astride seat.
Replace with stiff spring.
Bouncing

Rebound damping
SpringTurn adjuster clockwise (about 2 clicks) to increase
damping.
Replace with soft spring.
Stiff travel

High compression damp-
ing
Spring set length
SpringTurn adjuster counterclockwise (about 1/6 turn) to
decrease damping.
Set sunken length for 95 ~ 100 mm (3.7 ~ 3.9 in) when
one passenger is astride seat.
Replace with soft spring.