2002 YAMAHA YZ250F fuel

4 - 2
ENG

EXHAUST PIPE AND SILENCER
EC4S0000
EXHAUST PIPE AND SILENCER
Å
Except for USA
Extent of removal:
1
Silencer removal
2
Exhaust pipe removal
Extent of removal Order Part name Q’ty Remarks
EXHAUST PIPE AND
SILENCER REMOVAL
Preparation for removal Right side cover Refer to “SEAT, FUEL TANK AND SIDE
COVERS” section.
1 Bolt (silencer clamp) 1 Only loosening.
2 Bolt [silencer (front)] 1
3 Bolt [silencer (rear)] 1
4 Collar 1
5 Silencer 1
6 Silencer clamp 1
7 Nut (exhaust pipe) 1
8 Bolt (exhaust pipe) 1
9 Exhaust pipe 1
10 Gasket 2
1
2
2

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

4 - 7
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 Throttle cable cap 1
6 Clamp (air filter joint) 1 Loosen the screw (air filter joint).
7 Clamp (carburetor joint) 2 Loosen the screws (carburetor joint).
8 Carburetor assembly 1
9 Carburetor joint 1
1

4 - 10
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:
Pilot 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:
Carburetor body
Contamination → Clean.
NOTE:
Use a petroleum based solvent for cleaning.
Blow out all passages and jets with com-
pressed air.
Never use a wire.

4 - 20
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

4 - 29
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

4 - 78
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

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.
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.