Fork YAMAHA YZ125LC 2004 Service Manual

5-46
CHASSTEERING
Extent of removal Order Part name Q’ty Remarks
STEERING REMOVAL
Preparation for
Hold the machine by placing the
removalsuitable stand under the engine.
Number plate
Handlebar Refer to “HANDLEBAR” section.
Front fender
1 Steering shaft nut 1
2 Front fork 2 Refer to “FRONT FORK” section.
3 Handle crown 1
4 Ring nut 1 Use special tool.
Refer to “REMOVAL POINTS”.
5 Under bracket 1
6 Ball race cover 1
7 Bearing (upper) 1
8 Bearing (lower) 1 Refer to “REMOVAL POINTS”.
9 Ball race 2 Refer to “REMOVAL POINTS”. Extent of removal:1Under bracket removal 2Bearing removal
2
1
w
Support the machine securely so there is no dan-
ger of it falling over.
23 Nm (2.3 m•kg, 17 ft•lb)
145 Nm (14.5 m•kg, 105 ft•lb)
9Tighten ring nut.
38 Nm (3.8 m•kg, 27 ft•lb)
9Loosen it one turn.
9Retighten it.
7 Nm (0.7 m•kg, 5.1 ft•lb)
TIGHTENING STEPS:
20 Nm (2.0 m•kg, 14 ft•lb)
4Nm (0.4 m•kg, 2.9 ft•lb)
EC560000
STEERING
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5-49
CHASSTEERING
4. Install:
9Ring nut 1
Tighten the ring nut using the ring nut
wrench 2.
Refer to “STEERING HEAD INSPECTION
AND ADJUSTMENT” section in the CHAP-
TER 3.
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:
9Plain washer 1
7. Install:
9Front fork 1
9Handle crown 2
NOTE:
9Temporarily tighten the pinch bolts (under
bracket).
9Do not tighten the pinch bolts (handle crown)
yet.
8. Install:
9Plain washer 1
9Steering shaft nut 2
7 Nm (0.7 m•kg, 5.1 ft•lb)
145 Nm (14.5 m•kg, 105 ft•lb)
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5-50
CHASSTEERING
9. After tightening the nut, check the steering for
smooth movement. If not, adjust the steering
by loosening the ring nut little by little.
10. Adjust:
9Front fork top end a
11. Tighten:
9Pinch bolt (handle crown) 1
9Pinch bolt (under bracket) 2
cC
Tighten the under bracket to specified
torque. If torqued too much, it may cause
the front fork to malfunction.
Front fork top end (standard) a a
:
5 mm (0.20 in)
23 Nm (2.3 m•kg, 17 ft•lb)
20 Nm (2.0 m•kg, 14 ft•lb)
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7-16
TUNSETTING
EC722011
Front fork setting
The front fork setting should be made depending
on the rider’s feeling of an actual run and the cir-
cuit conditions.
The front fork setting includes the following three
factors:
1. Setting of air spring characteristics
9Change the fork oil level.
2. Setting of spring preload
9Change the spring.
9Install the adjustment washer.
3. Setting of damping force
9Change the compression damping.
9Change the rebound damping.
The spring acts on the load and the damp-
ing 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.
cC
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.
åAir spring characteristics in relation to oil level
change
∫Load
çStroke
1Max. oil level
2Standard oil level
3Min. oil level
Standard oil level:
125 mm (4.92 in)
Extent of adjustment:
105~135 mm (4.13~5.31 in)
From top of outer tube with
inner tube and damper rod fully
compressed without spring.
A
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7-17
TUNSETTING
EC727030
Spring preload adjustment
The spring preload is adjusted by installing the
adjustment washer 1between the spring seat 2
and fork spring 3.
cC
Do not install three or more adjustment
washers for each front fork.
w
Always adjust each front fork to the same
setting. Uneven adjustment can cause
poor handling and loss of stability.
åLoad
∫Fork stroke
aWithout adjustment washer (standard)
b1 adjustment washer
c2 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 position, 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:
9Change the rebound damping.
Turn out one or two clicks.
9Change the compression damping.
Turn in one or two clicks.
Standard washer quantity:
Zero adjustment washers
Extent of adjustment:
Zero ~ 2 adjustment washers
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7-19
TUNSETTING
EC72P010
Front fork setting parts
9Adjustment washer 1
9Front fork spring 2
[Equal pitch spring ]
[Unequal pitch spring ]
NOTE:
9The unequal pitch spring is softer in initial char-
acteristic than the equal pitch spring and is diffi-
cult to bottom out under full compression.
9The I.D. mark (slits) ais proved on the end of
the spring.
SPRING SPRINGI.D.
TYPE
RATE PART NUMBERMARK
(slits)
SOFT 0.398 5XE-23141-00 I
STD 0.408 5XE-23141-L0 –
0.418 5XE-23141-20 III
0.428 5XE-23141-30 IIII
0.438 5XE-23141-40 IIIII
STIFF 0.449 5XE-23141-50 I-I
0.459 5XE-23141-60 I-II
0.469 5XE-23141-70 I-III
0.479 5XE-23141-80 I-IIII
TYPE (thickness) PART NUMBER
T=2.3 mm (0.09 in) 5XE-23364-00
SPRING
SPRINGI.D.
TYPE RATE
PART NUMBERMARK
(approx.)(slits)
SOFT 0.398 5XE-23141-A0 V
0.418 5XE-23141-B0 V-I
0.438 5XE-23141-C0 V-II
0.459 5XE-23141-D0 V-III
STIFF 0.479 5XE-23141-E0 V-IIII
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7-24
TUNSETTING
EC72H010
Suspension setting
9Front fork
NOTE:
9If any of the following symptoms is experienced with the standard position as the base, make reset-
ting by reference to the adjustment procedure given in the same chart.
9Before any change, set the rear shock absorber sunken length to the standard figure 90~100 mm
(3.5~3.9 in).
Section
Symptom
JumpLarge
Medium Small Check Adjust
gap gap gap
Compression damping Turn adjuster counterclockwise (about 2 clicks)
Stiff over entire to decrease damping.
range111Oil level (oil amount) Decrease oil level by about 5~10 mm (0.2~0.4
in).
Spring Replace with soft spring.
Unsmooth Outer tube Check for any bends, dents, and other notice-
movement over 1111Inner tube able scars, etc. If any, replace affected parts.
entire range
Under bracket tightening Retighten to specified torque.
torque
Poor initial Rebound damping Turn adjuster counterclockwise (about 2 clicks)
movement1to decrease damping.
Oil seal Apply grease in oil seal wall.
Compression damping Turn adjuster clockwise (about 2 clicks) to in-
Soft over entire crease damping.
range, bottoming 11Oil level (oil amount) Increase oil level by about 5~10 mm (0.2~0.4
outin).
Spring Replace with stiff spring.
Stiff toward stroke
1Oil level (oil amount) Decrease oil level by about 5 mm (0.2 in).
end
Soft toward stroke
1Oil level (oil amount) Increase oil level by about 5 mm (0.2 in).
end, bottoming out
Stiff initial
1111Compression dampingTurn adjuster counterclockwise (about 2 clicks)
movement to decrease damping.
Compression damping Turn adjuster clockwise (about 2 clicks) to in-
crease damping.
Low front, tending Rebound damping Turn adjuster counterclockwise (about 2 clicks)
to lower front 11to decrease damping.
postureBalance with rear end Set sunken length for 95~100 mm (3.7~3.9 in)
when one passenger is astride seat (lower rear
posture).
Oil level (oil amount) Increase oil level by about 5 mm (0.2 in).
Compression damping Turn adjuster counterclockwise (about 2 clicks)
to decrease damping.
“Obtrusive” front, Balance with rear end Set sunken length for 90~95 mm (3.5~3.7 in)
tending to upper 11when one passenger is astride seat (upper rear
front postureposture).
Spring Replace with soft spring.
Oil lever (oil amount) Decrease oil level by about 5~10 mm (0.2~0.4
in).
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