2003 YAMAHA YZ125LC brake fluid

5-10
CHASFRONT BRAKE AND REAR BRAKE
Extent of removal Order Part name Q’ty Remarks
FRONT BRAKE REMOVAL
Preparation for
Hold the machine by placing the
removalsuitable stand under the engine.
Drain the brake fluid. Refer to “REMOVAL POINTS”.
1 Hose cover 1
2 Brake hose holder 1
3 Bolt (brake hose holder) 2 Only loosening.
4 Union bolt 2
5 Brake hose 1
6 Pad pin plug 1
Remove when loosening the pad pin.
7 Pad pin 1Loosen when disassembling the caliper.
8 Caliper 1
9 Brake lever 1
10 Master cylinder bracket 1
11 Master cylinder 1
EC5A0000
FRONT BRAKE AND REAR BRAKEEC5A8000
FRONT BRAKE
Extent of removal:1Brake hose removal2Caliper removal3Master cyilinder removal
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Support the machine securely so there is no dan-
ger of it falling over.
2
1
3
3
2
9 Nm (0.9 m•kg, 6.5 ft•lb)
6 Nm (0.6 m•kg, 4.3 ft•lb)
6 Nm (0.6 m•kg, 4.3 ft•lb)
6 Nm (0.6 m•kg, 4.3 ft•lb)
3 Nm (0.3 m•kg, 2.2 ft•lb)
18 Nm (1.8 m•kg, 13 ft•lb)
10 Nm (1.0 m•kg, 7.2 ft•lb)
7 Nm (0.7 m•kg, 5.1 ft•lb)16 Nm (1.6 m•kg, 11 ft•lb)
23 Nm (2.3 m•kg, 17 ft•lb)
30 Nm (3.0 m•kg, 22 ft•lb)
30 Nm (3.0 m•kg, 22 ft•lb)

5-11
CHASFRONT BRAKE AND REAR BRAKE
EC5A8100
REAR BRAKE
Extent of removal Order Part name Q’ty Remarks
REAR BRAKE REMOVAL
Preparation for
Hold the machine by placing the
removalsuitable stand under the engine.
Rear wheel Refer to “FRONT WHEEL AND
REAR WHEEL” section.
Drain the brake fluid. Refer to “REMOVAL POINTS”.
1 Brake pedal 1
2 Master cylinder 1
3 Brake hose holder 2
4 Union bolt 2
5 Brake hose 1
6 Pad pin plug 1
Remove when loosening the pad pin.
7 Pad pin 1Loosen when disassembling the caliper.
8 Caliper 1
Extent of removal:1Master cylinder removal2Brake hose removal3Caliper removal
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Support the machine securely so there is no dan-
ger of it falling over.
2
3
31
1
1 Nm (0.1 m•kg, 0.7 ft•lb)
30 Nm (3.0 m•kg, 22 ft•lb)
30 Nm (3.0 m•kg, 22 ft•lb)
3 Nm (0.3 m•kg, 2.2 ft•lb)
18 Nm (1.8 m•kg, 13 ft•lb)
6 Nm (0.6 m•kg, 4.3 ft•lb)
26 Nm (2.6 m•kg, 19 ft•lb)
10 Nm (1.0 m•kg, 7.2 ft•lb)
7 Nm (0.7 m•kg, 5.1 ft•lb)

5-14
CHASFRONT BRAKE AND REAR BRAKE
EC5A3000
REMOVAL POINTS
EC5A3101
Brake fluid
1. Remove:
[Front]
9Master cylinder cap 1
[Rear]
9Master cylinder cap 1
9Protector
NOTE:
Do not remove the diaphragm.
AFront
BRear
2. Connect the transparent hose 1to the
bleed screw 2and place a suitable contain-
er under its end.
AFront
BRear
3. Loosen the bleed screw and drain the brake
fluid while pulling the lever in or pushing
down on the pedal.
cC
9Do not reuse the drained brake fluid.
9Brake fluid may erode painted surfaces or
plastic parts. Always clean up spilled fluid
immediately.
EC533301
Caliper piston
1. Remove:
9Caliper piston
Use compressed air and proceed carefully.
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9Cover piston with rag and use extreme cau-
tion when expelling piston from cylinder.
9Never attempt to pry out piston.
AFront
BRear
Caliper piston removal steps:
9Insert a piece of rag into the caliper to lock
one caliper.
9Carefully force the piston out of the caliper
cylinder with compressed air.

5-15
CHASFRONT BRAKE AND REAR BRAKE
EC533402
Piston seal kit
1. Remove:
9Dust seal 1
9Piston seal 2
NOTE:
Remove the piston seals and dust seals by
pushing them with a finger.
cC
Never attempt to pry out piston seals and
dust seals.
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Replace the piston seals and dust seals
whenever a caliper is disassembled.
AFront
BRear
EC5A4000
INSPECTION
EC534112
Master cylinder
1. Inspect:
9Master cylinder inner surface a
Wear/ScratchesReplace master cylinder
assembly.
StainsClean.
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Use only new brake fluid.
AFront
BRear
2. Inspect:
9Diaphragm 1
Crack/DamageReplace.
AFront
BRear
3. Inspect:
9Master cylinder piston 1
9Master cylinder cup 2
Wear/Damage/Score marksReplace master
cylinder kit.
AFront
BRear

5-16
CHASFRONT BRAKE AND REAR BRAKE
EC534214
Caliper
1. Inspect:
9Caliper cylinder inner surface a
Wear/Score marksReplace caliper as-
sembly.
AFront
BRear
2. Inspect:
9Caliper piston 1
Wear/Score marksReplace caliper piston
assembly.
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Replace the piston seals and dust seals 2 2
whenever a caliper is disassembled.
EC534301
Brake hose
1. Inspect:
9Brake hose 1
Crack/DamageReplace.
EC5A5000
ASSEMBLY AND INSTALLATION
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9All internal parts should be cleaned in
new brake fluid only.
9Internal parts should be lubricated with
brake fluid when installed.
9Replace the piston seals and dust seals
whenever a caliper is disassembled.
EC5A5801
Caliper piston
1. Clean:
9Caliper
9Piston seal
9Dust seal
9Caliper piston
Clean them with brake fluid.

5-17
CHASFRONT BRAKE AND REAR BRAKE
2. Install:
9Piston seal 1
9Dust seal 2
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Always use new piston seals and dust
seals.
NOTE:
Fit the piston seals and dust seals onto the slot
on caliper correctly.
AFront
BRear
3. Install:
9Caliper piston 1
NOTE:
Apply the brake fluid on the piston wall.
cC
9Install the piston with its shallow
depressed side a a
facing the caliper.
9Never force to insert.
AFront
BRear
EC5A5700
Front caliper
1. Install:
9Pad support 1
9Brake pad 2
9Pad pin 3
NOTE:
9Install the brake pads with their projections
ainto the caliper recesses b.
9Temporarily tighten the pad pin at this point.

5-19
CHASFRONT BRAKE AND REAR BRAKE
2. Install:
9Disc cover 1
9Bolt (disc cover) 2
7 Nm (0.7 m•kg, 5.1 ft•lb)
3. Install:
9Caliper 1
9Rear wheel 2
Refer to “FRONT WHEEL AND REAR
WHEEL” section.
4. Tighten:
9Pad pin 3
5. Install:
9Pad pin plug 4
EC5A5220
Master cylinder kit
1. Clean:
9Master cylinder
9Master cylinder kit
Clean them with brake fluid.
2. Install:
9Master cylinder cup (primary) 1
9Master cylinder cup (secondary) 2
To master cylinder piston 3.
NOTE:
Apply the brake fluid on the master cylinder cup.
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After installing, cylinder cup should be in-
stalled as shown direction. Wrong installa-
tion cause improper brake performance.
AFront
BRear
18 Nm (1.8 m•kg, 13 ft•lb)
3 Nm (0.3 m•kg, 2.2 ft•lb)

5-20
CHASFRONT BRAKE AND REAR BRAKE
3. Install:
9Spring 1
To master cylinder piston 2.
NOTE:
Install the spring at the smaller dia. side.
AFront
BRear
4. Install:
[Front]
9Master cylinder kit 1
9Plain washer 2
9Circlip 3
9Master cylinder boot 4
To master cylinder 5.
[Rear]
9Master cylinder kit 1
9Push rod 2
9Circlip 3
9Master cylinder boot 4
To master cylinder 5.
NOTE:
9Apply the brake fluid on the master cylinder
kit.
9Apply the lithium soap base grease on the tip
of the push rod.
9When installing the circlip, use a long nose
circlip pliers.
AFront
BRear
EC5A5310
Front master cylinder
1. Install:
9Master cylinder 1
9Master cylinder bracket 2
9Bolt (master cylinder bracket) 3
NOTE:
9Install the bracket so that the arrow mark a
face upward.
9First tighten the bolts on the upper side of the
master cylinder bracket, and then tighten the
bolts on the lower side.
9 Nm (0.9 m•kg, 6.5 ft•lb)