brake YAMAHA YZ250F 2004 Service Manual

5 - 14
CHASFRONT BRAKE AND REAR BRAKE
EC5A3000
REMOVAL POINTS
Brake fluid
1. Remove:
[Front]
Brake master cylinder cap 1
[Rear]
Brake master cylinder cap 1
Protector
NOTE:
Do not remove the diaphragm.
ÅFront
ıRear
2. Connect the transparent hose 2 to the
bleed screw 1 and place a suitable con-
tainer under its end.
ÅFront
ıRear
Å
ı
3. Loosen the bleed screw and drain the
brake fluid while pulling the lever in or
pushing down on the pedal.
CAUTION:
Do not reuse the drained brake fluid.
Brake fluid may erode painted surfaces or
plastic parts. Always clean up spilled
fluid immediately.
ı
Å
Brake caliper piston
1. Remove:
Brake caliper piston
Use compressed air and proceed care-
fully.
WARNING
Cover piston with rag and use extreme
caution when expelling piston from cylin-
der.
Never attempt to pry out piston.
ÅFront
ıRear
Caliper piston removal steps:
Insert a piece of rag into the brake caliper
to lock one brake caliper.
Carefully force the piston out of the brake
caliper cylinder with compressed air.
Å
ı

5 - 15
CHASFRONT BRAKE AND REAR BRAKE
Brake caliper piston seal kit
1. Remove:
Dust seal 1
Piston seal 2
NOTE:
Remove the piston seals and dust seals by
pushing them with a finger.
CAUTION:
Never attempt to pry out piston seals and
dust seals.
WARNING
Replace the piston seals and dust seals
whenever a caliper is disassembled.
ÅFront
ıRear
Å
ı
EC5A4000
INSPECTION
Brake master cylinder
1. Inspect:
Brake master cylinder inner surface a
Wear/scratches → Replace master cyl-
inder assembly.
Stains → Clean.
WARNING
Use only new brake fluid.
ÅFront
ıRear
2. Inspect:
Diaphragm 1
Crack/damage → Replace.
ÅFront
ıRear
ı Å
ı
Å
3. Inspect: (front brake only)
Reservoir float 1
Damage → Replace.

5 - 16
CHAS
4. Inspect:
Brake master cylinder piston 1
Brake master cylinder cup 2
Wear/damage/score marks → Replace
brake master cylinder kit.
ÅFront
ıRear
Åı
Brake caliper
1. Inspect:
Brake caliper cylinder inner surface a
Wear/score marks → Replace brake
caliper assembly.
ÅFront
ıRear
ı Å
2. Inspect:
Brake caliper piston 1
Wear/score marks → Replace brake
caliper piston assembly.
WARNING
Replace the piston seals and dust seals 2
whenever a caliper is disassembled.
EC534301
Brake hose
1. Inspect:
Brake hose 1
Crack/damage → Replace.
EC5A5000
ASSEMBLY AND INSTALLATION
WARNING
All internal parts should be cleaned in
new brake fluid only.
Internal parts should be lubricated with
brake fluid when installed.
Replace the piston seals and dust seals
whenever a caliper is disassembled.
FRONT BRAKE AND REAR BRAKE

5 - 17
CHAS
Brake caliper piston
1. Clean:
Brake caliper
Piston seal
Dust seal
Brake caliper piston
Clean them with brake fluid.
2. Install:
Piston seal 1
Dust seal 2
WARNING
Always use new piston seals and dust
seals.
NOTE:
Fit the piston seals and dust seals onto the slot
on brake caliper correctly.
ÅFront
ıRear
3. Install:
Brake caliper piston 1
NOTE:
Apply the brake fluid on the piston wall.
CAUTION:
Install the piston with its shallow
depressed side a facing the brake cali-
per.
Never force to insert.
ÅFront
ıRear
Front brake caliper
1. Install:
Pad support 1
Brake pad 2
Pad pin 3
NOTE:
Install the brake pads with their projections
a into the brake caliper recesses b.
Temporarily tighten the pad pin at this point.
Å
ı
Å
ı
FRONT BRAKE AND REAR BRAKE

5 - 18
CHASFRONT BRAKE AND REAR BRAKE
2. Install:
Copper washer 1
Union bolt 2
WARNING
Always use new copper washers.
CAUTION:
Install the brake hose so that its pipe por-
tion a directs as shown and lightly
touches the projection b on the brake cali-
per.
T R..30 Nm (3.0 m · kg, 22 ft · lb)
3. Install:
Brake hose holder 1
Brake caliper 2
Bolt (brake caliper) 3
NOTE:
Fit the brake hose holder cut a over the pro-
jection b on the front fork and clamp the brake
hose.
4. Tighten:
Pad pin 4
5. Install:
Pad pin plug 5
Rear brake caliper
1. Install:
Pad support 1
Brake pad 2
Pad pin 3
NOTE:
Install the brake pads with their projections
a into the brake caliper recesses b.
Temporarily tighten the pad pin at this point.
T R..23 Nm (2.3 m · kg, 17 ft · lb)
T R..18 Nm (1.8 m · kg, 13 ft · lb)
T R..3 Nm (0.3 m · kg, 2.2 ft · lb)

5 - 19
CHASFRONT BRAKE AND REAR BRAKE
2. Install:
Brake disc cover 1
Bolt (brake disc cover) 2
T R..7 Nm (0.7 m · kg, 5.1 ft · lb)
3. Install:
Brake caliper 1
Rear wheel 2
Refer to “FRONT WHEEL AND REAR
WHEEL” section.
4. Tighten:
Pad pin 3
5. Install:
Pad pin plug 4
Brake master cylinder kit
1. Clean:
Brake master cylinder
Brake master cylinder kit
Clean them with brake fluid.
2. Install:
Brake master cylinder cup (primary) 1
Brake master cylinder cup (secondary)
2
To brake master cylinder piston 3.
NOTE:
Apply the brake fluid on the brake master cyl-
inder cup.
WARNING
After installing, cylinder cup should be
installed as shown direction. Wrong instal-
lation cause improper brake performance.
ÅFront
ıRear
T R..18 Nm (1.8 m · kg, 13 ft · lb)
T R..3 Nm (0.3 m · kg, 2.2 ft · lb)Åı
Åı

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

5 - 21
CHAS

FRONT BRAKE AND REAR BRAKE
2. Install:

Brake lever
1


Bolt (brake lever)
2


Nut (brake lever)
3

NOTE:

Apply the lithium soap base grease on the
brake lever sliding surface, bolt and contacting
surface of the brake master cylinder piston.
Rear brake master cylinder
1. Install:

Copper washer
1


Brake hose
2


Union bolt
3

WARNING

Always use new copper washers.
CAUTION:
Install the brake hose so that its pipe por-
tion
a
directs as shown and lightly
touches the projection
b
on the brake

master cylinder.
T R..6 Nm (0.6 m · kg, 4.3 ft · lb)
T R..6 Nm (0.6 m · kg, 4.3 ft · lb)
T R..30 Nm (3.0 m · kg, 22 ft · lb)

2. Install:

Brake master cylinder
1


Bolt (brake master cylinder)
2

3. Install:

Spring
1


Brake pedal
2


O-ring
3


Bolt (brake pedal)
4


Clip
5

NOTE:


Apply the lithium soap base grease on the
bolt, O-ring and brake pedal bracket.

Install the clip with its stopper portion
a
fac-
ing inward.
T R..11 Nm (1.1 m · kg, 8.0 ft · lb)
T R..26 Nm (2.6 m · kg, 19 ft · lb)

5 - 22
CHAS

FRONT BRAKE AND REAR BRAKE
4. Install:

Pin
1


Washer
2


Cotter pin
3

NOTE:

After installing, check the brake pedal height.
Refer to “REAR BRAKE ADJUSTMENT” sec-
tion in the CHAPTER 3.
Front brake hose
1. Install:

Brake hose
1

To brake hose holder
2
.
NOTE:

Before tightening the bolt (brake hose holder),
align the top
a
of the brake hose neck with the
brake hose holder bottom
b
. Then pass the
brake hose in front of the axle boss
c
and fit it
into the hose groove
d
so that the brake hose
does not contact the nut (wheel axle).
T R..10 Nm (1.0 m · kg, 7.2 ft · lb)

2. Install:

Brake hose cover
1


Washer
2


Bolt [brake hose cover (M8)]
3


Bolt [brake hose cover (M6)]
4
T R..16 Nm (1.6 m · kg, 11 ft · lb)
T R..7 Nm (0.7 m · kg, 5.1 ft · lb)
3. Pass the brake hose through the cable
guide 1, then through the guide a on
the protector 2.

5 - 23
CHASFRONT BRAKE AND REAR BRAKE
4. Install:
Copper washer 1
Brake hose 2
Union bolt 3
WARNING
Always use new copper washers.
CAUTION:
Install the brake hose so that its pipe por-
tion a directs as shown and lightly
touches the projection b on the brake
master cylinder.
T R..30 Nm (3.0 m · kg, 22 ft · lb)
Rear brake hose
1. Install:
Copper washer 1
Brake hose 2
Union bolt 3
WARNING
Always use new copper washers.
CAUTION:
Install the brake hose so that its pipe por-
tion a directs as shown and lightly
touches the projection b on the brake cali-
per.
T R..30 Nm (3.0 m · kg, 22 ft · lb)