2003 YAMAHA YZ250F steering

CHAPTER 4
ENGINE
SEAT, FUEL TANK
AND SIDE COVERS ................................. 4-1
EXHAUST PIPE AND SILENCER ............ 4-3
RADIATOR ................................................ 4-5
CARBURETOR ......................................... 4-8
CAMSHAFTS .......................................... 4-21
CYLINDER HEAD ................................... 4-30
VALVES AND VALVE SPRINGS ........... 4-33
CYLINDER AND PISTON ....................... 4-42
CLUTCH .................................................. 4-49
OIL FILTER ELEMENT, WATER PUMP
AND RIGHT CRANKCASE COVER ...... 4-56
BALANCER ............................................ 4-63
OIL PUMP ............................................... 4-66
KICK SHAFT AND SHIFT SHAFT .......... 4-71
CDI MAGNETO ....................................... 4-78
ENGINE REMOVAL ................................ 4-82
CRANKCASE AND CRANKSHAFT ....... 4-87
TRANSMISSION, SHIFT CAM
AND SHIFT FORK .................................. 4-96
CHAPTER 5
CHASSIS
FRONT WHEEL AND REAR WHEEL ...... 5-1
FRONT BRAKE AND REAR BRAKE ..... 5-10
FRONT FORK ......................................... 5-26
HANDLEBAR .......................................... 5-39
STEERING .............................................. 5-45
SWINGARM ............................................ 5-50
REAR SHOCK ABSORBER ................... 5-58

1 - 2
GEN
INFO
MACHINE IDENTIFICATION
EC120001
MACHINE IDENTIFICATION
There are two significant reasons for knowing
the serial number of your machine:
1. When ordering parts, you can give the
number to your Yamaha dealer for posi-
tive identification of the model you own.
2. If your machine is stolen, the authorities
will need the number to search for and
identify your machine.
EC121001
VEHICLE IDENTIFICATION NUMBER
The vehicle identification number 1 is
stamped on the right of the steering head pipe.
EC123001
ENGINE SERIAL NUMBER
The engine serial number 1 is stamped into
the elevated part of the right-side of the
engine.
EC124000
MODEL LABEL
The model label 1 is affixed to the frame
under the rider’s seat. This information will be
needed to order spare parts.

GEN
INFO
1 - 8
SPECIAL TOOLS
YU-33975, 90890-01403 Steering nut wrench
This tool is used when tighten the steering ring nut to
specification.YU-33975 90890-01403
YM-1423, 90890-01423 Damper rod holder
Use this tool to remove and install the damper rod.YM-1423 90890-01423
YM-01442, 90890-01442 Fork seal driver
This tool is used when install the fork oil seal.YM-01442 90890-01442
YU-3112-C, 90890-03112 Pocket tester
Use this tool to inspect the coil resistance, output
voltage and amperage.YU-3112-C 90890-03112
YU-8036-B
90890-03113Inductive tachometer
Engine tachometer
This tool is needed for observing engine rpm.YU-8036-B 90890-03113
YM-33277-A, 90890-03141 Timing light
This tool is necessary for checking ignition timing.YM-33277-A 90890-03141
YM-4019, 90890-04019 Valve spring compressor
This tool is needed to remove and install the valve
assemblies.YM-4019 90890-04019
YM-91042, 90890-04086 Clutch holding tool
This tool is used to hold the clutch when removing or
installing the clutch boss securing nut.YM-91042 90890-04086
YM-4111, 90890-04111
YM-4116, 90890-04116Valve guide remover
Intake 4.0 mm (0.16 in)
Exhaust 4.5 mm (0.18 in)
This tool is needed to remove and install the valve
guide.YM-4111
YM-411690890-04111
90890-04116
Part number Tool name/How to use Illustration

GEN
INFO
1 - 18
TORQUE-CHECK POINTS
TORQUE-CHECK POINTS
Frame construction
Combined seat and fuel tank
Exhaust system
Engine mounting
Steering Steering stem to
handlebar
Suspension Front Steering stem to front
fork
Rear For link type
Rear Installation of rear
shock absorber
Rear Installation of swing-
arm
Wheel Installation of wheel Front
Rear
Brake Front
Rear
Fuel system
Lubrication systemFrame to rear frame
Fuel tank to frame
Silencer to rear frame
Frame to engine
Engine bracket to engine
Engine bracket to frame
Steering stem to frame
Steering stem to upper bracket
Upper bracket to handlebar
Front fork to upper bracket
Front fork to lower bracket
Assembly of links
Link to frame
Link to rear shock absorber
Link to swingarm
Rear shock absorber to frame
Tightening of pivot shaft
Tightening of wheel axle
Tightening of axle holder
Tightening of wheel axle
Wheel to rear wheel sprocket
Brake caliper to front fork
Brake disc to wheel
Tightening of union bolt
Brake master cylinder to handlebar
Tightening of bleed screw
Brake pedal to frame
Brake disc to wheel
Tightening of union bolt
Brake master cylinder to frame
Tightening of bleed screw
Fuel tank to fuel cock
Tightening of oil hose clamp
NOTE:
Concerning the tightening torque, refer to
“MAINTENANCE SPECIFICATIONS” section
in the CHAPTER 2.

SPEC
2 - 12
MAINTENANCE SPECIFICATIONS
CHASSIS
Item Standard Limit
Steering system:
Steering bearing type Taper roller bearing ----
Front suspension: USA, CDN
AUS, NZ, ZAEUROPE
Front fork travel 300 mm (11.8 in)←----
Fork spring free length 460 mm (18.1 in)←455 mm (17.9 in)
Spring rate, STD K = 4.22 N/mm
(0.43 kg/mm,
24.1 lb/in)K = Approx.
4.22 N/mm
(0.43 kg/mm,
24.1 lb/in)----
Optional spring/spacer Yes←----
Oil capacity 563 cm
3
(19.8 Imp oz,
19.0 US oz) 573 cm3
(20.2 Imp oz,
19.4 US oz)----
Oil level 140 mm (5.51 in) 130 mm (5.12 in) ----

(From top of outer tube with inner
tube and damper rod fully com-
pressed without spring.)80 ~ 150 mm
(3.15 ~ 5.91 in)←----
Oil grade Suspension oil
“01”←----
Inner tube outer diameter 46 mm (1.81 in)←----
Front fork top end 5 mm (0.20 in)←----
Rear suspension: USA, CDN,
AUS, NZ, ZAEUROPE
Shock absorber travel 132 mm (5.20 in)←----
Spring free length 260 mm
(10.24 in)275 mm
(10.83 in)----
Fitting length 248 mm
(9.76 in)260 mm
(10.24 in)----
240.5~ 258.5 mm
(9.47 ~ 10.18 in)255.5~ 273.5 mm
(10.06 ~ 10.77 in)----
Spring rate, STD K = 46.0 N/mm
(4.70 kg/mm,
263.2 lb/in)K = Approx.
48.0 N/mm
(4.90 kg/mm,
274.4 lb/in)----
Optional spring Yes←----
Enclosed gas pressure 1,000 kPa
(10 kg/cm
2,
142 psi)←----
Swingarm:
Swingarm free play limit
End ---- 1.0 mm (0.04 in)

SPEC
2 - 14
MAINTENANCE SPECIFICATIONS
NOTE:
1. First, tighten the steering nut approximately 38 Nm (3.8 m • kg, 27 ft • lb) by using the steering
nut wrench, then loosen the steering nut one turn.
2. Retighten the steering nut 7 Nm (0.7 m • kg, 5.1 ft • lb). Part to be tightened Thread size Q’tyTightening torque
Nm m·kg ft·lb
Upper bracket and outer tube M8 × 1.25 4 23 2.3 17
Lower bracket and outer tube M8 × 1.25 4 20 2.0 14
Upper bracket and steering stem M24 × 1.0 1 145 14.5 105
Handlebar holder and upper bracket M8 × 1.25 4 28 2.8 20
Steering stem and steering ring nut M28 × 1.0 1 Refer to NOTE.
Front fork and front fork cap bolt M48 × 1.0 2 30 3.0 22
Front fork and base valve M30 × 1.0 2 55 5.5 40
Front fork cap bolt and damper rod M12 × 1.25 2 29 2.9 21
Front fork bleed screw and front fork cap bolt M5 × 0.8 2 1 0.1 0.7
Front fork and front fork protector M6 × 1.0 6 10 1.0 7.2
Front fork and brake hose guide M5 × 0.8 1 4 0.4 2.2
Front fork and brake hose holder M6 × 1.0 2 10 1.0 7.2
Front fork and brake hose cover (M8) M8 × 1.25 1 16 1.6 11
(M6) M6 × 1.0 1 7 0.7 5.1
Throttle grip cap M5 × 0.8 2 4 0.4 2.2
Front brake master cylinder M6 × 1.0 2 9 0.9 6.5
Brake lever mounting bolt M6 × 1.0 1 6 0.6 4.3
Brake lever mounting nut M6 × 1.0 1 6 0.6 4.3
Brake lever position locknut M6 × 1.0 1 5 0.5 3.6
Clutch lever holder M5 × 0.8 2 4 0.4 2.2
Clutch lever mounting bolt M6 × 1.0 1 2 0.2 1.4
Hot starter lever holder M5 × 0.8 2 4 0.4 2.9
Front brake master cylinder cap M4 × 0.7 2 2 0.2 1.4
Front brake hose union bolt M10 × 1.25 2 30 3.0 22
Front brake caliper M8 × 1.25 2 23 2.3 17
Pad pin plug M10 × 1.0 2 3 0.3 2.2
Front brake caliper and pad pin M10 × 1.0 1 18 1.8 13
Rear brake caliper and pad pin M10 × 1.0 1 18 1.8 13
Brake caliper and bleed screw M8 × 1.25 2 6 0.6 4.3
Front wheel axle and axle nut M16 × 1.5 1 105 10.5 75
Front wheel axle holder M8 × 1.25 4 23 2.3 17
Front brake disc M6 × 1.0 6 12 1.2 8.7
Rear brake disc M6 × 1.0 6 14 1.4 10
Brake pedal M8 × 1.25 1 26 2.6 19
Rear brake master cylinder M6 × 1.0 2 11 1.1 8.0
Rear brake master cylinder cap M4 × 0.7 2 2 0.2 1.4
Rear brake hose union bolt M10 × 1.25 2 30 3.0 2.2
Rear wheel axle and axle nut M20 × 1.5 1 125 12.5 90

3 - 3
INSP
ADJ
MAINTENANCE INTERVALS
FRONT FORKS
Inspect and adjust
Replace oil
Replace oil seal
●
●
●
●
● Suspension oil “01”
FRONT FORK OIL SEAL AND DUST
SEAL
Clean and lube
● ● Lithium base grease
REAR SHOCK ABSORBER
Inspect and adjust
Lube
Retighten
●
●
●
●
●
(After
rain ride)
●Molybdenum disulfide
grease
DRIVE CHAIN GUIDE AND ROLLERS
Inspect
● ●
SWINGARM
Inspect, lube and retighten
● ● Molybdenum disulfide
grease
RELAY ARM, CONNECTING ROD
Inspect, lube and retighten
● ● Molybdenum disulfide
grease
STEERING HEAD
Inspect free play and retighten
Clean and lube
Replace bearing
● ●
●
● Lithium base grease
TIRE, WHEELS
Inspect air pressure, wheel run-out,
tire wear and spoke looseness
Retighten sprocket bolt
Inspect bearings
Replace bearings
Lubricate
●
●
●
●
●
●
●
Lithium base grease
THROTTLE, CONTROL CABLE
Check routing and connection
Lubricate
Inspect and clean (throttle cable)
●
●
● ●

●
● Yamaha cable lube or
SAE 10W-30 motor oil
Inspect dirt and wear on
the throttle cable on the
carburetor side.
HOT STARTER, CLUTCH LEVER
Inspect free play
●
ItemAfter
break-inEvery
race
Every
third
(or
500 km)Every
fifth
(or
1,000 km)As re-
quiredRemarks

3 - 4
INSP
ADJ
PRE-OPERATION INSPECTION AND MAINTENANCE
EC320000
PRE-OPERATION INSPECTION AND MAINTENANCE
Before riding for break-in operation, practice or a race, make sure the machine is in good operating
condition.
Before using this machine, check the following points.
GENERAL INSPECTION AND MAINTENANCE
Item Routine Page
CoolantCheck that coolant is filled up to the radiator cap.
Check the cooling system for leakage.P.3-5 ~ 9
FuelCheck that a fresh gasoline is filled in the fuel tank. Check the
fuel line for leakage.P.1-13
Engine oilCheck that the oil level is correct. Check the crankcase and
frame oil line for leakage.P.3-13 ~ 16
Gear shifter and clutchCheck that gears can be shifted correctly in order and that the
clutch operates smoothly.P.3-9
Throttle grip/HousingCheck that the throttle grip operation and free play are correctly
adjusted. Lubricate the throttle grip and housing, if necessary.P.3-10
Brakes Check the play of front brake and effect of front and rear brake. P.3-24 ~ 30
Drive chainCheck drive chain slack and alignment. Check that the drive
chain is lubricated properly.P.3-31 ~ 33
WheelsCheck for excessive wear and tire pressure. Check for loose
spokes and have no excessive play.P.3-41 ~ 42
SteeringCheck that the handlebar can be turned smoothly and have no
excessive play.P.3-42 ~ 43
Front forks and rear shock
absorberCheck that they operate smoothly and there is no oil leakage. P.3-33 ~ 40
Cables (wires)Check that the clutch and throttle cables move smoothly. Check
that they are not caught when the handlebars are turned or
when the front forks travel up and down.—
Exhaust pipeCheck that the exhaust pipe is tightly mounted and has no
cracks.P.4-3
Rear wheel sprocket Check that the rear wheel sprocket tightening bolt is not loose. P.3-31
Lubrication Check for smooth operation. Lubricate if necessary. P.3-44
Bolts and nuts Check the chassis and engine for loose bolts and nuts. P.1-18
Lead connectorsCheck that the CDI magneto, CDI unit, and ignition coil are con-
nected tightly.P.1-6
SettingsIs the machine set suitably for the condition of the racing course
and weather or by taking into account the results of test runs
before racing? Are inspection and maintenance completely
done?P.7-1 ~ 22