2004 YAMAHA YZ125LC Front Fork

3-4
PRE-OPERATION INSPECTION AND MAINTENANCE
INSP
ADJ
EC320000
PRE-OPERATION INSPECTION AND MAINTENANCE
Before riding for break-in operation, practice or a race, make sure the machine is in good operating
condition.
Before using this machine, check the following points.
EC321000
GENERAL INSPECTION AND MAINTENANCE
Item Routine Page
Coolant Check that coolant is filled up to the radiator filler cap.
Check the cooling system for leakage.P3-5~9
Fuel Check that a fresh mixture of oil and gasoline is filled in
the fuel tank. Check the fuel line for leakage.P1-12
Transmission oil Check that the oil level is correct. Check the crankcase
for leakage.P3-12~14
Gear shifter and clutch Check that gears can be shifted correctly in order and
that the clutch operates smoothly.P3-9
Throttle grip/Housing Check that the throttle grip operation and free play
are correctly adjusted. Lubricate the throttle grip and P3-10~11
housing, if necessary.
Brakes Check the play of front brake and effect of front and
rear brake.P3-17~23
Chain Check chain slack and alignment. Check that the chain
is lubricated properly.P3-24~26
Wheels Check for excessive wear and tire pressure. Check for
loose spokes and have no excessive play.P3-34~35
Steering Check that the handlebar can be turned smoothly and
have no excessive play.P3-35~36
Front forks and Check that they operate smoothly and there is no oil
rear shock absorber leakage.P3-26~33
Cables (wires) Check that the clutch and throttle cables move smooth-
ly. Check that they are not caught when the handlebars —
are turned or when the front forks travel up and down.
Muffler Check that the muffler is tightly mounted and has no
cracks.P3-15~16
Sprocket Check that the driven sprocket tightening bolt is
not loose.P3-24
Lubrication Check for smooth operation. Lubricate if necessary. P3-37
Bolts and nuts Check the chassis and engine for loose bolts and nuts. P1-16
Lead connectors Check that the CDI magneto, CDI unit, and ignition coil
are connected tightly.P1-6
Settings Is the machine set suitably for the condition of the
racing course and weather or by taking into account the
P7-1~25
results of test runs before racing? Are inspection and
maintenance completely done?
5XE-9-30-3A 4/28/03 5:55 PM Page 14

3-20
FRONT BRAKE PAD INSPECTION AND REPLACEMENT
INSP
ADJ
9Loosen the pad pin 2.
9Remove the brake hose holder 3and
caliper 4from the front fork.
9Remove the pad pin and brake pads 5.
9Connect the transparent hose 6to the
bleed screw 7and place the suitable con-
tainer under its end.
9Loosen the bleed screw and push the
caliper piston in.
cC
Do not reuse the drained brake fluid.
9Tighten the bleed screw.
9Install the brake pads 8and pad pin.
NOTE:
9Install the brake pads with their projections
ainto the caliper recesses b.
9Temporarily tighten the pad pin at this point.
9Install the brake hose holder 9and caliper
0and tighten the pad pin q.
NOTE:
Fit the brake hose holder cut cover the pro-
jection
don the front fork and clamp the
brake hose.
Bleed screw:
6 Nm (0.6 m•kg, 4.3 ft•b)
Bolt (caliper):
23 Nm (2.3 m•kg, 17 ft•lb)
Pad pin:
18 Nm (1.8 m•kg, 13 ft•lb)
5XE-9-30-3B 4/16/03 10:24 AM Page 4

3-26
FRONT FORK INSPECTION
INSP
ADJ
3. Adjust:
9Drive chain slack
EC36C000
FRONT FORK INSPECTION
1. Inspect:
9Front fork smooth action
Operate the front brake and stroke the
front fork.
Unsmooth action/oil leakage Repair or
replace.
Drive chain slack adjustment steps:
9Loosen the axle nut 1and locknuts 2.
9Adjust chain slack by turning the
adjusters 3.
To tighten Turn adjuster 3 3
counter-
clockwise.
To loosen Turn adjuster 3 3
clockwise
and push wheel forward.
9Turn each adjuster exactly the same amount
to maintain correct axle alignment. (There are
marks aon each side of chain puller align-
ment.)
NOTE:
Turn the adjuster so that the chain is in line
with the sprocket, as viewed from the rear.
cC
Too small chain slack will overload the
engine and other vital parts; keep the
slack within the specified limits.
9Tighten the axle nut while pushing down the
drive chain.
9Tighten the locknuts.
Axle nut:
125 Nm (12.5 m•kg, 90 ft•lb)
Locknut:
16 Nm (1.6 m•kg, 11 ft•lb)
5XE-9-30-3B 4/16/03 10:24 AM Page 16

3-27
FRONT FORK OIL SEAL AND DUST SEAL CLEANING/
FRONT FORK INTERNAL PRESSURE RELIEVING/
FRONT FORK REBOUND DAMPING FORCE ADJUSTMENTINSP
ADJ
EC36D001
FRONT FORK OIL SEAL AND DUST SEAL
CLEANING
1. Remove:
9Protector
9Dust seal 1
NOTE:
Use a thin screw driver, and be careful not to
damage the inner fork tube and dust seal.
2. Clean:
9Dust seal a
9Oil seal b
NOTE:
9Clean the dust seal and oil seal after every run.
9Apply the lithium soap base grease on the in-
ner tube.
EC36H002
FRONT FORK REBOUND DAMPING FORCE
ADJUSTMENT
1. Adjust:
9Rebound damping force
By turning the adjuster 1.
Stiffer a a
Increase the rebound damping
force. (Turn the adjuster 1 1
in.)
Softer b b
Decrease the rebound
damping force. (Turn the
adjuster 1 1
out.)
EC36f000
FRONT FORK INTERNAL PRESSURE
RELIEVING
NOTE:
If the front fork initial movement feels stiff during
a run, relieve the front fork internal pressure.
1. Elevate the front wheel by placing a suitable
stand under the engine.
2. Remove the air bleed screw 1and release
the internal pressure from the front fork.
3. Install:
9Air bleed screw
1 Nm (0.1 m•kg, 0.7 ft•lb)
5XE-9-30-3B 4/16/03 10:24 AM Page 18

3-28
FRONT FORK COMPRESSION DAMPING FORCE
ADJUSTMENTINSP
ADJ
cC
Do not force the adjuster past the minimum
or maximum extent of adjustment. The ad-
juster may be damaged.
w
Always adjust each front fork to the same
setting. Uneven adjustment can cause
poor handling and loss of stability.
EC36J001
FRONT FORK COMPRESSION DAMPING
FORCE ADJUSTMENT
1. Remove:
9Rubber cap
2. Adjust:
9Compression damping force
By turning the adjuster 1.
Stiffer a a
Increase the compression
damping force. (Turn the
adjuster 1 1
in.)
Softer b b
Decrease the compression
damping force. (Turn the
adjuster 1 1
out.)
Minimum
20 clicks out
(from maximum
position)
9STANDARD POSITION:
This is the position which is back by the spe-
cific number of clicks from the fully turned-in
position.
Extent of adjustment:
Maximum
Fully turned in
position
Standard position:
12 clicks out
*11 clicks out
*For EUROPE
5XE-9-30-3B 4/16/03 10:24 AM Page 20

3-29
REAR SHOCK ABSORBER INSPECTION
INSP
ADJ
9STANDARD POSITION:
This is the position which is back by the spe-
cific number of clicks from the fully turned-in
position.
cC
Do not force the adjuster past the minimum
or maximum extent of adjustment. The ad-
juster may be damaged.
w
Always adjust each front fork to the same
setting. Uneven adjustment can cause
poor handling and loss of stability.
3. Install:
9Rubber cap
EC36K000
REAR SHOCK ABSORBER INSPECTION
1. Inspect:
9Swingarm smooth action
Abnormal noise/Unsmooth action 
Grease the pivoting points or repair the
pivoting points.
Damage/Oil leakage Replace.
Minimum
20 clicks out
(from maximum
position)
Extent of adjustment:
Maximum
Fully turned in
position
Standard position:
12 clicks out
*13 clicks out
*For EUROPE
5XE-9-30-3B 4/16/03 10:24 AM Page 22

3-35
STEERING HEAD INSPECTION AND ADJUSTMENT
INSP
ADJ
2. Inspect:
9Bearing free play
Exist play Replace.
EC36U070
STEERING HEAD INSPECTION AND
ADJUSTMENT
1. Elevate the front wheel by placing a suitable
stand under the engine.
2. Check:
9Steering shaft
Grasp the bottom of the forks and gently
rock the fork assembly back and forth.
Free play Adjust steering head.
3. Check:
9Steering smooth action
Turn the handlebar lock to lock.
Unsmooth action Adjust steering ring
nut.
4. Adjust:
9Steering ring nut
Steering ring nut adjustment steps:
9Remove the number plate.
9Remove the handlebar and handle crown.
9Loosen the ring nut 1using the ring nut
wrench 2.
9Tighten the ring nut 3using ring nut wrench
4.
NOTE:
9Apply the lithium soap base grease on the
thread of the steering shaft.
9Set the torque wrench to the ring nut wrench
so that they form a right angle.
Ring nut wrench:
YU-33975/90890-01403
5XE-9-30-3B 4/16/03 10:24 AM Page 34

5-6
CHASFRONT WHEEL AND REAR WHEEL
5. Install:
9Wheel axle 1
NOTE:
Apply the lithium soap base grease on the wheel
axle.
6. Install:
9Nut (wheel axle) 1
7. Tighten:
9Bolt (axle holder) 1
NOTE:
Before tightening the bolt, fit the wheel axle to
the axle holder by stroking the front fork several
times with the front brake applied.
8. Install:
9Brake hose 1
To brake hose holder 2.
NOTE:
Before tightening the bolt (brake hose holder),
align the top aof the brake hose neck with the
brake hose holder bottom b. Then pass the
brake hose in front of the axle boss cand fit it
into the hose groove dso that the brake hose
does not contact the nut (wheel axle).
105 Nm (10.5 m•kg, 75 ft•lb)
23 Nm (2.3 m•kg, 17 ft•lb)
10 Nm (1.0 m•kg, 7.2 ft•lb)
5XE-9-30-5A 4/28/03 6:06 PM Page 12