2005 YAMAHA YZ250F warning

4 - 6
ENGRADIATOR
EC456000
HANDLING NOTE
WARNING
Do not remove the radiator cap when the
engine and radiator are hot. Scalding hot
fluid and steam may be blown out under
pressure, which could cause serious
injury.
When the engine has cooled, open the radi-
ator cap by the following procedure:
Place a thick rag, like a towel, over the radi-
ator cap, slowly rotate the cap counter-
clockwise to the detent. This procedure
allows any residual pressure to escape.
When the hissing sound has stopped,
press down on the cap while turning coun-
terclockwise and remove it.
EC454000
INSPECTION
EC444100
Radiator
1. Inspect:
Radiator core 1
Obstruction → Blow out with compressed
air through rear of the radiator.
Bent fin → Repair/replace.
EC455000
ASSEMBLY AND INSTALLATION
Radiator
1. Install:
O-ring 1
Radiator pipe 2
Bolt (radiator pipe) 3
NOTE:
Apply the lithium soap base grease on the O-
ring.
2. Install:
Radiator breather hose 1
Radiator hose 4 (longer) 2
Radiator hose 2 (shorter) 3
To left radiator 4.
T R..10 Nm (1.0 m · kg, 7.2 ft · lb)

4 - 82
ENGENGINE REMOVAL
EC4M0000
ENGINE REMOVAL
Extent of removal Order Part name Q’ty Remarks
ENGINE REMOVAL
Preparation for removal Hold the machine by placing the
suitable stand under the frame.
WARNING
Support the machine securely so
there is no danger of it falling over.
Seat and fuel tank Refer to “SEAT, FUEL TANK AND SIDE
COVERS” section.
Carburetor Refer to “CARBURETOR” section.
Exhaust pipe and silencer Refer to “EXHAUST PIPE AND
SILENCER” section.
Clutch cable Disconnect at engine side.
Radiator Refer to “RADIATOR” section.
Shift pedal Refer to “KICK SHAFT AND SHIFT
SHAFT” section.
Cylinder head breather hose and
oil tank breather hoseRefer to “CAMSHAFTS” section.
Drain the engine oil Refer to “ENGINE OIL REPLACEMENT”
section in the CHAPTER 3.

5 - 1
CHAS
EC500000
CHASSIS
EC590000
FRONT WHEEL AND REAR WHEEL
EC598000
FRONT WHEEL
FRONT WHEEL AND REAR WHEEL
Extent of removal:
1 Front wheel removal
2 Wheel bearing removal
3 Brake disc removal
Extent of removal Order Part name Q’ty Remarks
FRONT WHEEL REMOVAL
WARNING
Support the machine securely so
there is no danger of it falling over. Preparation for removal Hold the machine by placing the
suitable stand under the engine.
1 Bolt (axle holder) 4 Only loosening.
2 Nut (front wheel axle) 1
3 Front wheel axle 1
4 Front wheel 1
5 Collar 2
6 Oil seal 2
7 Bearing 2 Refer to “REMOVAL POINTS”.
8 Brake disc 1
2
31
3

5 - 2
CHAS
EC598100
REAR WHEEL
Extent of removal:
1 Rear wheel removal
2 Wheel bearing removal
3 Brake disc removal
Extent of removal Order Part name Q’ty Remarks
REAR WHEEL REMOVAL
WARNING
Support the machine securely so
there is no danger of it falling over. Preparation for removal Hold the machine by placing the
suitable stand under the engine.
1 Nut (rear wheel axle) 1
2 Rear wheel axle 1
3 Drive chain puller 2
4 Rear wheel 1 Refer to “REMOVAL POINTS”.
5 Collar 2
6 Rear wheel sprocket 1
7 Oil seal 2
8 Circlip 1
9 Bearing 2 Refer to “REMOVAL POINTS”.
10 Brake disc 1
2
31
3
FRONT WHEEL AND REAR WHEEL

5 - 4
CHASFRONT WHEEL AND REAR WHEEL
EC514200
Wheel axle
1. Measure:
Wheel axle bends
Out of specification → Replace.
Use the dial gauge 1.
NOTE:
The bending value is shown by one half of the
dial gauge reading.
WARNING
Do not attempt to straighten a bent axle.
Wheel axle bending limit:
0.5 mm (0.020 in)
EC594200
Brake disc
1. Measure:
Brake disc deflection (only rear brake
disc)
Use the dial gauge 1.
Out of specification → Inspect wheel
runout.
If wheel runout is in good condition,
replace the brake disc.
2. Measure:
Brake disc thickness a
Out of limit → Replace.
Brake disc deflection limit:
Rear:
: 0.15 mm (0.006 in)
Brake disc thickness:
Front:
3.0 mm (0.12 in)
: 2.5 mm (0.10 in)
Rear:
4.0 mm (0.16 in)
: 3.5 mm (0.14 in)

5 - 10
CHASFRONT BRAKE AND REAR BRAKE
EC5A0000
FRONT BRAKE AND REAR BRAKE
EC5A8000
FRONT BRAKE
Extent of removal:
1 Brake hose removal
2 Brake caliper removal
3 Brake master cylinder removal
Extent of removal Order Part name Q’ty Remarks
FRONT BRAKE REMOVAL
WARNING
Support the machine securely so
there is no danger of it falling over. Preparation for removal Hold the machine by placing the
suitable stand under the engine.
Drain the brake fluid. Refer to “REMOVAL POINTS”.
1 Brake hose holder (protector) 2
2 Brake hose holder (brake caliper) 1
3 Union bolt 2
4 Brake hose 1
5 Pad pin plug 1 Remove when loosening the pad pin.
6 Pad pin 1 Loosen when disassembling the brake
caliper.
7 Brake caliper 1
8Brake lever 1
9 Brake master cylinder bracket 1
10 Brake master cylinder 1
3
3
2
2
1

5 - 11
CHAS
EC5A8100
REAR BRAKE
Extent of removal:
1 Brake master cylinder removal
2 Brake hose removal
3 Brake caliper removal
Extent of removal Order Part name Q’ty Remarks
REAR BRAKE REMOVAL
WARNING
Support the machine securely so
there is no danger of it falling over. Preparation for removal Hold the machine by placing the
suitable 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 Brake 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 1 Loosen when disassembling the brake
caliper.
8 Brake caliper 1
3
32
1
1
FRONT BRAKE AND REAR BRAKE

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.
È
Front
ÉRear
2. Connect the transparent hose 2 to the
bleed screw 1 and place a suitable con-
tainer under its end.
È
Front
ÉRear
È
É
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.
ÈÉ
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.
È
Front
ÉRear
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.
È
É