2001 YAMAHA YZ250F fuel

4 - 4
ENG

RADIATOR
EC450001
RADIATOR
Extent of removal:
1
Radiator removal
Extent of removal Order Part name Q’ty Remarks
RADIATOR REMOVAL
Preparation for removal Drain the coolant. Refer to “COOLANT REPLACEMENT”
section in the CHAPTER 3.
Seat and fuel tank Refer to “SEAT, FUEL TANK AND SIDE
COVERS” section.
1 Radiator guard 2
2 Radiator hose clamp 8 Only loosening.
3 Radiator hose 1 1
4 Left radiator 1
5 Radiator hose 3 1
6 Right radiator 1
7 Radiator hose 2 1
8 Radiator hose 4 1
9 Radiator breather hose 1
10 Radiator pipe 1
1

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ENGCARBURETOR
CARBURETOR
Extent of removal:1 Carburetor removal
Extent of removal Order Part name Q’ty Remarks
CARBURETOR REMOVAL
Preparation for removal Seat and fuel tank Refer to “SEAT, FUEL TANK AND SIDE
COVERS” section.
1 Clamp 1
2 Throttle position sensor lead cou-
pler1
3 Throttle cable cover 1
4 Throttle cable 2
5 Clamp (air filter joint) 1 Loosen the screw (air filter joint).
6 Clamp (carburetor joint) 2 Loosen the screws (carburetor joint).
7 Carburetor assembly 1
8 Carburetor joint 1
1

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ENGCARBURETOR
HANDLING NOTE
CAUTION:
Do not loosen the screws (throttle position
sensor) 1 except when changing the throt-
tle position sensor due to failure because it
will cause a drop in engine performance.
REMOVAL POINTS
Pilot screw
1. Remove:
lPilot screw 1
NOTE:
To optimize the fuel flow at a small throttle
opening, each machine’s pilot screw has been
individually set at the factory. Before removing
the pilot screw, turn it in fully and count the
number of turns. Record this number as the
factory-set number of turns out.
INSPECTION
Carburetor
1. Inspect:
lCarburetor body
Contamination ® Clean.
NOTE:
lUse a petroleum based solvent for cleaning.
Blow out all passages and jets with com-
pressed air.
lNever use a wire.

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ENGCAMSHAFTS
CAMSHAFTS
CYLINDER HEAD COVER
Extent of removal:1 Cylinder head cover removal
Extent of removal Order Part name Q’ty Remarks
CYLINDER HEAD COVER
REMOVAL
Preparation for removal Seat and fuel tank Refer to “SEAT, FUEL TANK AND SIDE
COVERS” section.
Carburetor Refer to “CARBURETOR” section.
1 Spark plug 1
2 Cylinder head breather hose 1
3 Oil tank breather hose 1
4 Bolt (cylinder head cover) 2
5 Cylinder head cover 1
6 Cylinder head cover gasket 1
7Timing chain guide (top side)
1
1

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ENGCYLINDER HEAD
CYLINDER HEAD
Extent of removal:1 Cylinder head removal
Extent of removal Order Part name Q’ty Remarks
CYLINDER HEAD REMOVAL
Preparation for removal Seat and fuel tank Refer to “SEAT, FUEL TANK AND SIDE
COVERS” section.
Exhaust pipe and silencer Refer to “EXHAUST PIPE AND
SILENCER” section.
Radiator hose 1 Disconnect at cylinder head side.
Carburetor Refer to “CARBURETOR” section.
Camshaft Refer to “CAMSHAFTS” section.
Upper engine bracket Refer to “ENGINE REMOVAL” section.
1 Radiator pipe 1
2 Decompression cable guide 1
3 Oil delivery pipe 1
4 Nut 2
5 Bolt [L=135 mm (5.31 in)] 2
6 Bolt [L=145 mm (5.71 in)] 2
7 Cylinder head 1 Disconnect the decompression cable.
8 Timing chain guard (exhaust side) 1
9 Bolt (decompression shaft) 1
10 Decompression shaft 1
1

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ENGCDI MAGNETO
EC4L0000
CDI MAGNETO
Extent of removal:1 CDI magneto removal
Extent of removal Order Part name Q’ty Remarks
CDI MAGNETO REMOVAL
Preparation for removal Seat and fuel tank Refer to “SEAT, FUEL TANK AND SIDE
COVERS” section.
Bolt (left radiator) Refer to “RADIATOR” section.
Disconnect the CDI magneto lead.
Shift pedal Refer to “KICK SHAFT AND SHIFT
SHAFT” section.
1 Left crankcase cover 1
2 Nut (rotor) 1 Use special tool.
Refer to “REMOVAL POINTS”.
3 Rotor 1
4 Stator 1
5Woodruff key
1
1

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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 nodanger 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.
Decompression cable and guide 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.

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CHASHANDLEBAR
7. Install:
lEngine stop switch 1
lClutch lever holder 2
lBolt (clutch lever holder) 3
lDecompression lever holder 4
lBolt (decompression lever holder) 5
lClamp 6
T R..4 Nm (0.4 m · kg, 2.9 ft · lb)
T R..4 Nm (0.4 m · kg, 2.9 ft · lb)
NOTE:
lThe engine stop switch, clutch lever holder,
decompression lever holder and clamp
should be installed according to the dimen-
sions shown.
lPass the engine stop switch lead in the mid-
dle of the clutch holder.
8. Install:
lClutch cable 1
lDecompression cable 2
NOTE:
Apply the lithium soap base grease on the
clutch cable end and decompression cable
end.
9. Adjust:
lClutch lever free play
Refer to “CLUTCH ADJUSTMENT”
section in the CHAPTER 3.
lDecompression lever free play
Refer to “DECOMPRESSION LEVER
ADJUSTMENT” section in the CHAP-
TER 3.
B
2
1
10. Clamp the clamp portion a of the num-
ber plate to the handlebar.
11. Insert the end of the fuel tank breather
hose 1 into the hole of the number plate.