2003 YAMAHA YZ250F oil

4 - 68
ENGOIL PUMP
INSPECTION
Oil pump
1. Inspect:
Oil pump drive gear 1
Oil pump drive shaft 2
Rotor housing 3
Oil pump cover 4
Cracks/wear/damage → Replace.
1
32
4
2. Measure:
Tip clearance a
(between the inner rotor 1 and outer
rotor 2)
Side clearance b
(between the outer rotor 2 and rotor
housing 3)
Housing and rotor clearance c
(between the rotor housing 3 and
rotors 1 2)
Out of specification → Replace the oil
pump assembly.
Tip clearance a:
0.12 mm or less
(0.0047 in or less)
: 0.20 mm (0.008 in)
Side clearance b:
0.09 ~ 0.17 mm (0.0035 ~ 0.0067 in)
: 0.24 mm (0.009 in)
Housing and rotor clearance c:
0.03 ~ 0.10 mm (0.0012 ~ 0.0039 in)
: 0.17 mm (0.0067 in)
3. Check:
Unsmooth → Repeat steps #1 and #2
or replace the defective parts.

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ENGOIL PUMP
ASSEMBLY AND INSTALLATION
Oil pump
1. Install:
Oil pump drive shaft 1
Washer 2
Dowel pin 3
Inner rotor 1 4
NOTE:
Apply the engine oil on the oil pump drive
shaft and inner rotor 1.
Fit the dowel pin into the groove in the inner
rotor 1.
2. Install:
Outer rotor 1 1
NOTE:
Apply the engine oil on the outer rotor 1.
3. Install:
Oil pump cover 1
Screw (oil pump cover) 2
Dowel pin 3
Inner rotor 2 4
Circlip 5
NOTE:
Apply the engine oil on the inner rotor 2.
Fit the dowel pin into the groove in the inner
rotor 2.
T R..2 Nm (0.2 m · kg, 1.4 ft · lb)

4 - 70
ENG
4. Install:
Outer rotor 2 1
Dowel pin 2
Oil pump assembly 3
Bolt (oil pump assembly)
[L = 25 mm (0.94 in)] 4
Bolt (oil pump assembly)
[L = 30 mm (1.18 in)] 5
NOTE:
Apply the engine oil on the outer rotor 2.
T R..10 Nm (1.0 m · kg, 7.2 ft · lb)
T R..10 Nm (1.0 m · kg, 7.2 ft · lb)
5. Install:
Oil pump drive gear 1
Washer 2
Circlip 3
NOTE:
Apply the engine oil on the oil pump drive gear
inner circumference.
OIL PUMP

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ENGKICK SHAFT AND SHIFT SHAFT
KICK SHAFT AND SHIFT SHAFT
Extent of removal:1 Kick shaft removal2 Kick shaft disassembly
3 Shift shaft removal4 Segment removal
Extent of removal Order Part name Q’ty Remarks
KICK SHAFT AND SHIFT
SHAFT REMOVAL
Preparation for removal Oil pump Refer to “OIL PUMP” section.
1 Kick idle gear 1
2 Kick shaft assembly 1 Refer to “REMOVAL POINTS”.
3 Spring guide 1
4 Torsion spring 1
5 Ratchet wheel 1
6 Kick gear 1
7 Kick shaft 1
8 Washer 1
9 Shift pedal 1
10 Shift shaft 1
11Collar
1
3
2
1
4
1

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ENGKICK SHAFT AND SHIFT SHAFT
EC4B5111
Stopper lever
1. Install:
Torsion spring 1
Stopper lever 2
Bolt (stopper lever) 3
NOTE:
Align the stopper lever roller with the slot on
segment.
Shift guide and shift lever assembly
1. Install:
Spring 1
Pawl pin 2
Pawl 3
To shift lever 4.
NOTE:
Apply the engine oil on the spring, pawl pin
and pawl.
2. Install:
Shift lever assembly 1
To shift guide 2.
T R..10 Nm (1.0 m · kg, 7.2 ft · lb)
3. Install:
Shift lever assembly 1
Shift guide 2
NOTE:
The shift lever assembly is installed at the
same time as the shift guide.
Apply the engine oil on the bolt (segment)
shaft.
4. Install:
Bolt (shift guide) 1
T R..10 Nm (1.0 m · kg, 7.2 ft · lb)

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ENGKICK SHAFT AND SHIFT SHAFT
Shift shaft
1. Install:
Roller 1
Collar 2
Torsion spring 3
Shift shaft 4
NOTE:
Apply the engine oil on the roller and shift
shaft.
2. Install:
Shift pedal 1
Bolt (shift pedal) 2
NOTE:
When installing the shift pedal onto the shift
shaft, be sure that the center of the shift pedal
is about 1 mm (0.04 in) a above the top of the
footrest.
T R..12 Nm (1.2 m · kg, 8.7 ft · lb)
Kick shaft assembly
1. Install:
Kick gear 1
Washer 2
Circlip 3
Ratchet wheel 4
Spring 5
Washer 6
Circlip 7
To kick shaft 8.
NOTE:
Apply the molybdenum disulfide oil on the
inner circumferences of the kick gear and
ratchet wheel.
Align the punch mark a on the ratchet wheel
with the punch mark b on the kick shaft.
2. Install:
Torsion spring 1
To kick shaft 2.
NOTE:
Make sure the stopper a of the torsion spring
fits into the hole b on the kick shaft.

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ENGKICK SHAFT AND SHIFT SHAFT
3. Install:
Spring guide 1
NOTE:
Slide the spring guide into the kick shaft, make
sure the groove a in the spring guide fits on
the stopper of the torsion spring.
4. Install:
Kick shaft assembly 1
Washer 2
NOTE:
Apply the molybdenum disulfide grease on
the contacting surfaces of the kick shaft stop-
per a and stopper plate 3.
Apply the engine oil on the kick shaft.
Slide the kick shaft assembly into the crank-
case and make sure the kick shaft stopper a
fits into the stopper plate.
5. Hook:
Torsion spring 1
NOTE:
Turn the torsion spring clockwise and hook
into the proper hole a in the crankcase.
Kick idle gear
1. Install:
Kick idle gear 1
Washer 2
Circlip 3
NOTE:
Apply the engine oil on the kick idle gear
inner circumference.
Install the kick idle gear with its depressed
side a toward you.

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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 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.