2000 YAMAHA YZ426F Front fork

5 - 48
CHAS
4. Install:
lPlain washer 1
lRing nut 2
Tighten the ring nut using the ring nut
wrench 3.
Refer to “STEERING HEAD INSPEC-
TION AND ADJUSTMENT” section in
the CHAPTER 3.
T R..7 Nm (0.7 m · kg, 5.1 ft · lb)
5. Check the steering shaft by turning it lock
to lock. If there is any binding, remove
the steering shaft assembly and inspect
the steering bearings.
6. Install:
lPlain washer 1
7. Install:
lFront fork 1
lHandle crown 2
NOTE:
lTemporarily tighten the pinch bolts (under
bracket).
lDo not tighten the pinch bolts (handle crown)
yet.
8. Install:
lPlain washer 1
lSteering shaft nut 2
T R..145 Nm (14.5 m · kg, 105 ft · lb)
STEERING

5 - 49
CHASSTEERING
9. After tightening the nut, check the steer-
ing for smooth movement. If not, adjust
the steering by loosening the ring nut little
by little.
10. Adjust:
lFront fork top end a
Front fork top end (standard) a:
Zero mm (Zero in)
11. Tighten:
lPinch bolt (handle crown) 1
lPinch bolt (under bracket) 2
ACHTUNG:CAUTION:
Tighten the under bracket to specified
torque. If torqued too much, it may cause
the front fork to malfunction.
T R..23 Nm (2.3 m · kg, 17 ft · lb)
T R..20 Nm (2.0 m · kg, 14 ft · lb)

7 - 12
TUNSETTING
EC722011
Front fork setting
The front fork setting should be made depend-
ing on the rider’s feeling of an actual run and
the circuit conditions.
The front fork setting includes the following
three factors:
1. Setting of air spring characteristics
lChange the fork oil level.
2. Setting of spring preload
lChange the spring.
lInstall the adjustment washer.
3. Setting of damping force
lChange the compression damping.
lChange the rebound damping.
The spring acts on the load and the
damping force acts on the cushion
travel speed.
EC723001
Change in level and characteristics of fork
oil
Damping characteristic near the final stroke
can be changed by changing the fork oil
amount.
CAUTION:
Adjust the oil level in 5 mm (0.2 in) incre-
ments or decrements. Too low oil level
causes the front fork to produce a noise at
full rebound or the rider to feel some pres-
sure on his hands or body. Alternatively,
too high oil level will develop unexpectedly
early oil lock with the consequent shorter
front fork travel and deteriorated perfor-
mance an characteristics. Therefore, adjust
the front fork within the specified range.
Air spring characteristics in relation to oil level
change
õLoad
‚Stroke
1Max. oil level
2Standard oil level
3Min. oil level
Standard oil level:
130 mm (5.12 in)
Extent of adjustment:
80 ~ 150 mm (3.15 ~ 5.91 in)
From top of outer tube with
inner tube and damper rod fully
compressed without spring.

7 - 13
TUNSETTING
EC727020
Spring preload adjustment
The spring preload is adjusted by installing the
adjustment washer 1 between the fork spring
2 and damper rod 3.
CAUTION:
Do not install three or more adjustment
washers for each front fork.
WARNING
Always adjust each front fork to the same
setting. Uneven adjustment can cause poor
handling and loss of stability.
Load
õFork stroke
1Without adjustment washer (standard)
21 adjustment washer
32 adjustment washers
Standard washer quantity:
Zero adjustment washers
Extent of adjustment:
Zero ~ 2 adjustment washers
EC72A001
Setting of spring after replacement
As the front fork setting can be easily affected
by rear suspension, take care so that the
machine front and rear are balanced (in posi-
tion, etc.) when setting the front fork.
1. Use of soft spring
Generally a soft spring gives a soft riding
feeling. Rebound damping tends to
become stronger and the front fork may
sink deeply over a series of gaps.
To set a soft spring:
lChange the rebound damping.
Turn out one or two clicks.
lChange the compression damping.
Turn in one or two clicks.

7 - 15
TUN
EC72P000
Front fork setting parts
lAdjustment washer 1
lFront fork spring 2
[Equal pitch spring]
* For EUROPE
[Unequal pitch spring]
NOTE:
lThe unequal pitch spring is softer in initial
characteristic than the equal pitch spring and
is difficult to bottom out under full compres-
sion.
lThe I.D. mark (slits) a is proved on the end
of the spring.TYPE (thickness) PART NUMBER
T = 2.3 mm (0.09 in) 4SS-23364-L0
TYPESPRING
RATESPRING
PART NUMBERI.D.
MARK
(slits)
SOFT0.380
0.390
0.400
0.410
0.420
0.430
0.4404SS-23141-10
4SS-23141-20
4SS-23141-30
4SS-23141-40
4SS-23141-50
4SS-23141-60
4SS-23141-70I-I
I-II
I-III
I
II
III
IIII
*STD 0.450 5BE-23141-L0 –
STD 0.460 5GR-23141-L0 –
STIFF 0.470 5GR-23141-00 II-II
TYPESPRING
RATE
(approx.)SPRING
PART NUMBERI.D.
MARK
(slits)
SOFT
STIFF0.400
0.410
0.420
0.430
0.4405ET-23141-20
5ET-23141-00
5ET-23141-30
5ET-23141-10
5ET-23141-40V
V-I
V-II
V-III
V-IIII
SETTING

7 - 20
TUNSETTING
EC72H002
Suspension setting
lFront fork
NOTE:
lIf 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.
lBefore 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
CCC
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
CCCC
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
C
Rebound damping
Oil sealTurn adjuster counterclockwise (about 2 clicks) to
decrease damping.
Apply grease in oil seal wall.
Soft over entire range,
bottoming out
CC
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
COil level (oil amount) Decrease oil level by about 5 mm (0.2 in).
Soft toward stroke end,
bottoming out
COil level (oil amount) Increase oil level by about 5 mm (0.2 in).
Stiff initial movement
CCCCCompression dampingTurn adjuster counterclockwise (about 2 clicks) to
decrease damping.
Low front, tending to
lower front posture
CC
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
CC
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).