2002 YAMAHA YZ125LC length

4-32
ENGCLUTCH AND PRIMARY DRIVEN GEAR
EC493000
REMOVAL POINTS
EC483211
Clutch boss
1. Remove:
9Nut 1
9Lock washer 2
9Clutch boss 3
NOTE:
Straighten the lock washer tab and use the
clutch holding tool 4, 5to hold the clutch boss.
å
For USA and CDN
∫
Except for USA and CDN
EC494000
INSPECTION
EC484100
Clutch housing and boss
1. Inspect:
Clutch housing 1
Cracks/Wear/Damage  Replace.
9Clutch boss 2
Scoring/Wear/Damage Replace.
EC484201
Primary driven gear
1. Check:
9Circumferential play
Free play exists Replace.
9Gear teeth a
Wear/ Damage Replace.
EC484400
Clutch spring
1. Measure:
9Clutch spring free length a
Out of specification Replace springs as
a set.
Clutch holding tool:
YM-91042................................
4 4
90890-04086............................5 5
Clutch spring free length:
Standard
41.2 mm 39.2 mm
(1.622 in) (1.543 in)
å
∫å
5NY-9-30-4B 5/23/01 8:48 PM Page 30

5-31
CHASFRONT FORK
EC554200
Base valve
1. Inspect:
9Valve assembly 1
Wear/DamageReplace.
9O-ring 2
DamageReplace.
EC554400
Fork spring
1. Measure:
9Fork spring free length a
Out of specificationReplace.
EC554502
Inner tube
1. Inspect:
9Inner tube surface a
Score marksRepair or replace.
Use #1,000 grit wet sandpaper.
Damaged oil lock pieceReplace.
9Inner tube bends
Out of specificationReplace.
Use the dial gauge 1.
NOTE:
The bending value is shown by one half of the
dial gauge reading.
w
Do not attempt to straighten a bent inner
tube as this may dangerously weaken the
tube.
EC554600
Outer tube
1. Inspect:
9Outer tube 1
Score marks/Wear/DamageReplace.
Standard
460 mm 455 mm
(18.1 in) (17.9 in)Fork spring free length:
Inner tube bending limit:
0.2 mm (0.008 in)
5NY-9-30-5B 5/23/01 9:05 PM Page 10

5-63
CHASREAR SHOCK ABSORBER
EC5852B4
Rear shock absorber
1. Install:
9Dust seal 1
9O-ring 2
9Collar 3
NOTE:
9Apply the molybdenum disulfide grease on the
bearing.
9Apply the lithium soap base grease on the dust
seals, O-rings and collars.
2. Install:
9Bush 1
9Collar 2
9Dust seal 3
NOTE:
9Apply the molybdenum disulfide grease on the
bearing.
9Apply the lithium soap base grease on the
bush, collars and dust seals.
9Install the dust seals with their lips facing out-
ward.
3. Adjust:
9Spring length (installed) a
*For EUROPE
NOTE:
The length of the spring (installed) changes 1.5
mm (0.06 in) per turn of the adjuster.
cC
Never attempt to turn the adjuster beyond
the maximum or minimum setting.
4. Tighten:
9Locknut 1
Spring length (installed) a
a
:
Standard
length
248 mm (9.76 in)
*262 mm (10.31 in)Extent of
adjustment
240.5~258.5 mm
(9.47~10.18 in)
*255.5~273.5 mm
(10.06~10.77 in)
5NY-9-30-5D 5/23/01 9:15 PM Page 24

7-19
TUNSETTING
EC72B000
Rear suspension setting
The rear suspension setting should be made
depending on the rider’s feeling of an actual run
and the circuit conditions.
The rear suspension setting includes the follow-
ing two factors:
1. Setting of spring preload
9Change the set length of the spring.
9Change the spring.
2. Setting of damping force
9Change the rebound damping.
9Change the compression damping.
EC72C001
Choosing set length
1. Place a stand or block under the engine to
put the rear wheel above the floor, and mea-
sure the length abetween the rear wheel
axle center and the rear fender holding bolt.
2. Remove the stand or block from the engine
and with a rider astride the seat, measure
the sunken length bbetween the rear wheel
axle center and the rear fender holding bolt.
3. Loosen the locknut 1and make adjustment
by turning the spring adjuster 2to achieve
the standard figure from the subtraction of
the length bfrom the length a.
Standard figure:
90~100 mm (3.5~3.9 in)
5NY-9-30-7B 5/23/01 9:22 PM Page 14

7-20
TUNSETTING
NOTE:
9If 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.
9If 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.
EC72G020
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
9Set the soft spring for less rebound damp-
ing 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
9Set the soft spring for more rebound damp-
ing 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 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.
5NY-9-30-7B 5/23/01 9:22 PM Page 16

7-21
TUNSETTING
cC
When using a rear cushion other than cur-
rently installed, use the one whose overall
length
a 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
∫Rider weight
1Soft
2Standard
3Stiff
Length a a
of standard shock:
490.5 mm (19.31 in)
5NY-9-30-7B 5/23/01 9:22 PM Page 18

7-22
TUNSETTING
EC72Q011
Rear shock absorber setting parts
9Rear shock spring 1
[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. color ais marked at the end of the
spring.
9Extent of adjustment (spring length)
SPRING SPRINGI.D.SPRING
TYPE
RATE PART NUMBERCOLORFREE
/POINTLENGTH
SOFT 4.4 5DH-22212-70Brown/1260
STD 4.6 5DH-22212-10Green/1260
4.8 5DH-22212-20 Red/1 260
5.0 5DH-22212-30 Black/1 260
STIFF 5.2 5DH-22212-40 Blue/1 260
5.4 5DH-22212-50
Yellow/1265
5.6 5DH-22212-60 Pink/1 265
SPRING
SPRINGI.D.SPRING
TYPE RATE
PART NUMBERCOLORFREE
(approx.)/POINTLENGTH
SOFT 4.6 5ET-22212-20 Green/2 275
*STD 4.8 5ET-22212-00 Red/2 275
5.0 5ET-22212-10 Black/2 275
STIFF 5.2 5ET-22212-30 Blue/2 275
5.4 5ET-22212-40
Yellow/2 275
*For EUROPE
SPRING FREE EXTENT OF
LENGTH ADJUSTMENT b
260mm (10.24in)240.5~258.5mm(9.47~10.18in)
265mm (10.43in)245.5~263.5mm(9.67~10.37in)
275mm (10.83in)255.5~273.5mm(10.06~10.77in)
5NY-9-30-7B 5/23/01 9:22 PM Page 20

7-23
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).
5NY-9-30-7B 5/23/01 9:22 PM Page 22