torque YAMAHA YZ250F 2008 Owners Manual

CONTENTS
CHAPTER 1
GENERAL INFOR-
MATION
DESCRIPTION ................. 1-1
MACHINE
IDENTIFICATION ............. 1-2
INCLUDED PARTS .......... 1-2
IMPORTANT
INFORMATION................. 1-2
CHECKING OF
CONNECTION .................. 1-3
SPECIAL TOOLS ............. 1-4
CONTROL FUNCTIONS .. 1-8
STARTING AND
BREAK-IN ........................ 1-8
TORQUE-CHECK
POINTS........................... 1-11
CLEANING AND
STORAGE ...................... 1-12
CHAPTER 2
SPECIFICATIONS
GENERAL
SPECIFICATIONS ............ 2-1
MAINTENANCE
SPECIFICATIONS ............ 2-3
TIGHTENING
TORQUES ...................... 2-10
LUBRICATION
DIAGRAMS .................... 2-16
CABLE ROUTING
DIAGRAM ....................... 2-18
CHAPTER 3
REGULAR INSPEC-
TION AND AD-JUSTMENTS
MAINTENANCE
INTERVALS ...................... 3-1
PRE-OPERATION
INSPECTION AND
MAINTENANCE................ 3-5
ENGINE ............................ 3-6
CHASSIS ........................ 3-14
ELECTRICAL ................. 3-23
CHAPTER 4 ENGINE
SEAT, FUEL TANK AND
SIDE COVERS.................. 4-1
EXHAUST PIPE AND
SILENCER ........................ 4-3
RADIATOR ....................... 4-5
CARBURETOR................. 4-7
CAMSHAFTS.................. 4-14
CYLINDER HEAD........... 4-19
VALVES AND VALVE
SPRINGS ........................ 4-21
CYLINDER AND
PISTON ........................... 4-25
CLUTCH ......................... 4-29
OIL FILTER ELEMENT
AND WATER PUMP ....... 4-34
BALANCER .................... 4-38
OIL PUMP ....................... 4-40
KICK SHAFT AND
SHIFT SHAFT ................. 4-44
CDI MAGNETO............... 4-49
ENGINE REMOVAL ....... 4-51
CRANKCASE AND
CRANKSHAFT ............... 4-55
TRANSMISSION, SHIFT
CAM AND SHIFT
FORK .............................. 4-61
CHAPTER 5CHASSIS
FRONT WHEEL AND
REAR WHEEL ..................5-1
FRONT BRAKE AND
REAR BRAKE ..................5-6
FRONT FORK ................. 5-16
HANDLEBAR..................5-24
STEERING ......................5-28
SWINGARM ....................5-32
REAR SHOCK
ABSORBER ....................5-37
CHAPTER 6
ELECTRICAL
ELECTRICAL
COMPONENTS AND
WIRING DIAGRAM ...........6-1
IGNITION SYSTEM...........6-2
THROTTLE POSITION
SENSOR SYSTEM ...........6-5
CHAPTER 7
TUNING
ENGINE.............................7-1
CHASSIS ..........................7-6

1-10
STARTING AND BREAK-IN
BREAK-IN PROCEDURES
1. Before starting the engine, fill the fuel tank with the fuel.
2. Perform the pre-operation checks
on the machine.
3. Start and warm up the engine. Check the idle speed, and check
the operation of the controls and
the engine stop switch. Then, re-
start the engine and check its op-
eration within no more than 5
minutes after it is restarted.
4. Operate the machine in the lower
gears at moderate throttle open-
ings for five to eight minutes.
5. Check how the engine runs when
the machine is ridden with the
throttle 1/4 to 1/2 open (low to me-
dium speed) for about one hour.
6. Restart the engine and check the operation of the machine through-
out its entire operating range. Re-
start the machine and operate it
for about 10 to 15 more minutes.
The machine will now be ready to
race.
• After the break-in or before each race, you must check the entire
machine for loose fittings and
fasteners as per "TORQUE-
CHECK POINTS". Tighten all
such fasteners as required.
• When any of the following parts
have been replaced, they must
be broken in.
CYLINDER AND CRANKSHAFT:
About one hour of break-in oper-
ation is necessary.
PISTON, RING, VALVES, CAM-
SHAFTS AND GEARS:
These parts require about 30
minutes of break-in operation at
half-throttle or less. Observe the
condition of the engine carefully
during operation.

1-11
TORQUE-CHECK POINTS
TORQUE-CHECK POINTS
Concerning the tightening torque, refer to "TIGHTENING TORQUES" section in the CHAPTER 2.
Frame constructionFrame to rear frame
Combined seat and fuel tank Fuel tank to frame
Exhaust system Silencer to rear frame
Engine mounting Frame to engine
Engine bracket to engine
Engine bracket to frame
Steering Steering stem to handlebar Steering stem to frame
Steering stem to upper bracket
Upper bracket to handlebar
Suspension Front Steering stem to front fork Front fork to upper bracket
Front fork to lower bracket
Rear For link type Assembly of links
Link to frame
Link to rear shock absorber
Link to swingarm
Installation of rear shock absorber Rear shock absorber to frame
Installation of swingarm Tightening of pivot shaft
Wheel Installation of wheel Front Tightening of wheel axle
Tightening of axle holder
Rear Tightening of wheel axle Wheel to rear wheel sprocket
Brake Front Brake caliper to front fork
Brake disc to wheel
Tightening of union bolt
Brake master cylinder to handlebar
Tightening of bleed screw
Tightening of brake hose holder
Rear Brake pedal to frame Brake disc to wheel
Tightening of union bolt
Brake master cylinder to frame
Tightening of bleed screw
Tightening of brake hose holder
Fuel system Fuel tank to fuel cock
Lubrication system Tightening of oil hose clamp

2-10
TIGHTENING TORQUES
TIGHTENING TORQUES
ENGINE
â–³- marked portion shall be checked for torque tightening after break-in or before each race.
Pickup coil resistance (color)248–372 Ωat 20 °C (68 °F) (White–Red) ----
CDI unit-model/manufacturer 5XC-L0/YAMAHA (For USA and CDN) ----
5XC-M0/YAMAHA (For EUROPE, AUS,
NZ and ZA) ----
Ignition coil: Model/manufacturer 5UL-10/DENSO----
Minimum spark gap 6 mm (0.24 in)----
Primary coil resistance 0.08–0.10
Ωat 20 °C (68 °F)----
Secondary coil resistance 4.6–6.8 k
Ωat 20 °C (68 °F)----
Item
StandardLimit
Part to be tightened Thread size Q'tyTightening torque
Nm m•kg ft•lb
Spark plug M10S × 1.0 1 13 1.3 9.4
Camshaft cap M6 × 1.0 10 10 1.0 7.2
Cylinder head blind plug screw M12 × 1.0 1 28 2.8 20
Cylinder head (stud bolt) M6 × 1.0 2 7 0.7 5.1
Cylinder head (stud bolt) M8 × 1.25 1 15 1.5 11
Cylinder head (bolt) M9 × 1.25 4 38 3.8 27
Cylinder head (nut) M6 × 1.0 2 10 1.0 7.2
Cylinder head cover M6 × 1.0 2 10 1.0 7.2
Cylinder M6 × 1.0 1 10 1.0 7.2
Balancer weight M6 × 1.0 2 10 1.0 7.2
Balancer shaft driven gear M14 × 1.0 1 50 5.0 36
Timing chain guide (intake side) M6 × 1.0 2 10 1.0 7.2
Timing chain tensioner M6 × 1.0 2 10 1.0 7.2
Timing chain tensioner cap bolt M6 × 1.0 1 7 0.7 5.1
Impeller M8 × 1.25 1 14 1.4 10
Radiator hose clamp M6 × 1.0 10 2 0.2 1.4
Coolant drain bolt M6 × 1.0 1 10 1.0 7.2
Water pump housing M6 × 1.0 4 10 1.0 7.2
Radiator M6 × 1.0 6 10 1.0 7.2
Radiator pipe M6 × 1.0 1 10 1.0 7.2
Oil pump cover M4 × 0.7 1 2 0.2 1.4
Oil pump M6 × 1.0 3 10 1.0 7.2
Oil filter element drain bolt M6 × 1.0 1 10 1.0 7.2
Oil filter element cover M6 × 1.0 2 10 1.0 7.2
Oil strainer (crankcase) M6 × 1.0 2 10 1.0 7.2
Oil delivery pipe 1 (M10) M10 × 1.25 1 20 2.0 14
Oil delivery pipe 1 (M8) M8 × 1.25 2 18 1.8 13
Oil hose M6 × 1.0 2 8 0.8 5.8
△Oil hose clamp —1 2 0.2 1.4
Oil strainer (oil tank) M6 × 1.0 1 9 0.9 6.5

2-11
TIGHTENING TORQUES
Oil tank drain boltM8 × 1.25 1 18 1.8 13
Oil tank (upper) M6 × 1.0 1 7 0.7 5.1
Oil tank and frame M6 × 1.0 3 9 0.9 6.5
Carburetor joint clamp M4 × 0.7 2 3 0.3 2.2
Air filter joint clamp M6 × 1.0 1 3 0.3 2.2
Throttle cable adjust bolt and locknut M6 × 0.75 1 4 0.4 2.9
Throttle cable (pull) M6 × 1.0 1 4 0.4 2.9
Throttle cable (return) M12 × 1.0 1 11 1.1 8.0
Throttle cable cover M5 × 0.8 2 4 0.4 2.9
Hot starter plunger M12 × 1.0 1 2 0.2 1.4
Hot starter cable adjust bolt and locknut M6 × 0.75 1 4 0.4 2.9
△Air filter case M6 × 1.0 2 8 0.8 5.8
Air filter joint and air filter case M5 × 0.8 1 4 0.4 2.9
Air filter element M6 × 1.0 1 2 0.2 1.4
Exhaust pipe M8 × 1.25 2 20 2.0 14
△Exhaust pipe protector M6 × 1.0 3 10 1.0 7.2
△SilencerM8 × 1.25 2 30 3.0 22
Silencer clamp M8 × 1.25 1 16 1.6 11
Crankcase M6 × 1.0 11 12 1.2 8.7
Crankcase bearing stopper M6 × 1.0 11 10 1.0 7.2
Crankcase bearing stopper (crankshaft) M6 × 1.0 4 14 1.4 10
Oil level check window holder M6 × 1.0 1 10 1.0 7.2
Left crankcase cover M6 × 1.0 8 10 1.0 7.2
Right crankcase cover M6 × 1.0 8 10 1.0 7.2
Clutch cover M6 × 1.0 7 10 1.0 7.2
Crankcase oil drain bolt M10 × 1.25 1 20 2.0 14
△Crankshaft end accessing screw M32 × 1.5 1 — — —
△Timing mark accessing screwM14 × 1.5 1 — — —
Drive chain sprocket cover M6 × 1.0 2 8 0.8 5.8
Kick shaft ratchet wheel guide M6 × 1.0 2 12 1.2 8.7
Kickstarter crank M8 × 1.25 1 33 3.3 24
Primary drive gear M18 × 1.0 1 75 7.5 54
Clutch spring M6 × 1.0 5 10 1.0 7.2
Clutch boss M16 × 1.0 1 60 6.0 43
Clutch cable locknut M8 × 1.25 1 7 0.7 5.1
Clutch cable adjust bolt and locknut M6 × 0.75 1 4 0.4 2.9
Push lever shaft M6 × 1.0 1 10 1.0 7.2
Drive sprocket M18 × 1.0 1 75 7.5 54
Drive axle oil seal stopper M6 × 1.0 2 10 1.0 7.2
Segment M8 × 1.25 1 30 3.0 22
Shift guide M6 × 1.0 2 10 1.0 7.2
Stopper lever M6 × 1.0 1 10 1.0 7.2
Shift pedal M6 × 1.0 1 12 1.2 8.7
Part to be tightened
Thread size Q'tyTightening torque
Nm m•kg ft•lb

2-12
TIGHTENING TORQUES
CHASSIS
â–³- marked portion shall be checked for torque tightening after break-in or before each race.
Part to be tightenedThread size Q'tyTightening torque
Nm m•kg ft•lb
△Upper bracket and outer tube M8 × 1.25 4 21 2.1 15
△Lower bracket and outer tube M8 × 1.25 4 21 2.1 15
△Upper bracket and steering stem M24 × 1.0 1 145 14.5 105
△Handlebar upper holder and handlebar lower holderM8 × 1.25 4 28 2.8 20
△Handlebar lower holder and upper bracketM10 × 1.25 2 34 3.4 25
△Steering stem and steering ring nut M28 × 1.0 1Refer to NOTE.
Front fork and damper assembly M51 × 1.5 2 30 3.0 22
Front fork and adjuster M22 × 1.25 2 55 5.5 40
Damper assembly and base valve M42 × 1.5 2 29 2.9 21
Adjuster and damper assembly M12 × 1.25 2 29 2.9 21
Front fork bleed screw and base valve M5 × 0.8 2 1 0.1 0.7
△Front fork and front fork protector M6 × 1.0 6 5 0.5 3.6
△Lower bracket and brake hose guideM6 × 1.0 1 4 0.4 2.9
△Front fork protector and brake hose holderM6 × 1.0 2 7 0.7 5.1
Throttle grip cap M5 × 0.8 2 4 0.4 2.9
△Front brake master cylinderM6 × 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 2.9
Clutch lever mounting nut M6 × 1.0 1 4 0.4 2.9
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 boltM10 × 1.25 2 30 3.0 22
△Front brake caliper M8 × 1.25 2 28 2.8 20
Pad pin plug M10 × 1.0 2 3 0.3 2.2
△Front brake caliper and pad pinM10 × 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 screwM8 × 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 holderM8 × 1.25 4 21 2.1 15
△Front brake disc M6 × 1.0 6 12 1.2 8.7
△Rear brake disc M6 × 1.0 6 14 1.4 10
△Footrest bracket and frameM10 × 1.25 4 55 5.5 40
△Brake pedal M8 × 1.25 1 26 2.6 19
△Rear brake master cylinder M6 × 1.0 2 10 1.0 7.2
Rear brake master cylinder cap M4 × 0.7 2 2 0.2 1.4
△Rear brake hose union boltM10 × 1.25 2 30 3.0 22
△Rear wheel axle and axle nut M20 × 1.5 1 125 12.5 90
△Nipple (spoke) —72 3 0.3 2.2
△Rear wheel sprocket M8 × 1.25 6 42 4.2 30

2-13
TIGHTENING TORQUES
△Rear brake disc coverM6 × 1.0 2 10 1.0 7.2
△Rear brake caliper protector M6 × 1.0 2 7 0.7 5.1
Drive chain puller adjust bolt and locknut M8 × 1.25 2 19 1.9 12
Engine mounting:
△Engine and engine bracket (front) M10 × 1.25 1 53 5.3 38
△Engine and frame (lower) M10 × 1.25 1 53 5.3 38
△Upper engine bracket and frame M8 × 1.25 4 34 3.4 25
△Lower engine bracket and frameM8 × 1.25 4 38 3.8 27
△Engine and engine bracket (upper)M10 × 1.25 1 55 5.5 40
Lower engine guard M6 × 1.0 3 10 1.0 7.2
△Right engine guardM6 × 1.0 1 10 1.0 7.2
CDI unit bracket M6 × 1.0 2 7 0.7 5.1
Cable guide and CDI unit bracket M5 × 0.8 2 4 0.4 2.9
Cable guide and frame M5 × 0.8 1 5 0.5 3.6
△Pivot shaft and nutM16 × 1.5 1 85 8.5 61
△Relay arm and swingarmM14 × 1.5 1 70 7.0 50
△Relay arm and connecting rod M14 × 1.5 1 80 8.0 58
△Connecting rod and frame M14 × 1.5 1 80 8.0 58
△Rear shock absorber and frameM10 × 1.25 1 56 5.6 40
△Rear shock absorber and relay armM10 × 1.25 1 53 5.3 38
△Rear frame (upper) M8 × 1.25 1 38 3.8 27
△Rear frame (lower) M8 × 1.25 2 32 3.2 23
△Swingarm and brake hose holder M5 × 0.8 4 2 0.2 1.4
Swingarm and patch M4 × 0.7 4 2 0.2 1.4
Upper drive chain tensioner M8 × 1.25 1 16 1.6 11
Lower drive chain tensioner M8 × 1.25 1 16 1.6 11
Drive chain support M6 × 1.0 3 7 0.7 5.1
△Seal guard and swingarmM5 × 0.8 4 6 0.6 4.3
△Fuel tank mounting boss and frameM10 × 1.25 1 20 2.0 14
△Fuel tank M6 × 1.0 2 9 0.9 6.5
△Fuel cockM6 × 1.0 2 4 0.4 2.9
Seat set bracket and fuel tank M6 × 1.0 1 7 0.7 5.1
Fuel tank bracket and fuel tank M6 × 1.0 4 7 0.7 5.1
△Air scoop and fuel tankM6 × 1.0 6 7 0.7 5.1
△Air scoop and radiator guard (lower) M6 × 1.0 2 7 0.7 5.1
△Front fenderM6 × 1.0 4 7 0.7 5.1
△Rear fender (front) M6 × 1.0 2 7 0.7 5.1
△Rear fender (rear) M6 × 1.0 2 16 1.6 11
△Side coverM6 × 1.0 2 7 0.7 5.1
Seat M8 × 1.25 2 23 2.3 17
△Number plate M6 × 1.0 1 7 0.7 5.1
Part to be tightened
Thread size Q'tyTightening torque
Nm m•kg ft•lb

2-14
TIGHTENING TORQUES
1. First, tighten the steering ring nut approximately 38 Nm (3.8 m•kg, 27 ft•lb) by using the steering nut wrench, then loosen the steering ring nut one turn.
2. Retighten the steering ring nut 7 Nm (0.7 m•kg, 5.1 ft•lb).
ELECTRICAL
Part to be tightened Thread size Q'ty Tightening torque
Nm m•kg ft•lb
Stator M6 × 1.0 3 10 1.0 7.2
Rotor M12 × 1.25 1 56 5.6 40
Neutral switch M5 × 0.8 2 4 0.4 2.9

2-15
TIGHTENING TORQUES
GENERAL TORQUE
SPECIFICATIONS
This chart specifies torque for stan-
dard fasteners with standard I.S.O.
pitch threads. Torque specifications
for special components or assem-
blies are included in the applicable
sections of this book. To avoid
warpage, tighten multi-fastener as-
semblies in a crisscross fashion, in
progressive stages, until full torque is
reached. Unless otherwise specified,
torque specifications call for clean,
dry threads. Components should be
at room temperature.A. Distance between flats
B. Outside thread diameter
DEFINITION OF UNITS
A
(Nut) B
(Bolt
) TORQUE SPECIFI-
CATION
Nm m•kg ft•lb
10
mm 6 mm 6 0.6 4.3
12
mm 8 mm 15 1.5 11
14
mm 10
mm 30 3.0 22
17
mm 12
mm 55 5.5 40
19
mm 14
mm 85 8.5 61
22
mm 16
mm 130 13 94
Unit
Read Definition Measure
mm
millimeter 10-3 meterLength
cmcentimeter 10-2 meterLength
kgkilogram 103 gramWeight
NNewton 1 kg × m/sec2Force
NmNewton meterN × mTorque
m•kgMeter kilogram m × kgTorque
PaPascal N/m2Pressure
N/mmNewton per millimeter N/mm Spring rate
LLiter—Volume or capacity
cm3Cubic centimeter —Volume or capacity
r/minRevolution per minute —Engine speed

3-21
CHASSIS
3. Check:• Steering smooth actionTurn the handlebar lock to lock.
Unsmooth action
→Adjust steer-
ing ring nut.
4. Adjust: • Steering ring nut
Steering ring nut adjustment
steps:
a. Remove the number plate.
b. Remove the handlebar and upper
bracket.
c. Loosen the steering ring nut "1"
using the steering nut wrench "2".
d. Tighten the steering ring nut "3" using steering nut wrench "4".
• Apply the lithium soap base grease
on the thread of the steering stem.
• Set the torque wrench to the steer- ing nut wrench so that they form a
right angle.
e. Loosen the steering ring nut one
turn.
f. Retighten the steering ring nut us- ing the steering nut wrench.
Avoid over-tightening.
g. Check the steering stem by turn-ing it lock to lock. If there is any
binding, remove the steering stem
assembly and inspect the steer-
ing bearings.
h. Install the washer "5", upper bracket "6", washer "7", steering
stem nut "8", handlebar "9", han-
dlebar upper holder "10" and
number plate "11".
• The handlebar upper holder should be installed with the punched mark
"a" forward.
• Install the handlebar so that the marks "b" are in place on both
sides.
• Install the handlebar so that the pro- jection "c" of the handlebar upper
holder is positioned at the mark on
the handlebar as shown.
• Insert the end of the fuel breather
hose "12" into the hole in the steer-
ing stem.
First tighten the bolts on the front
side of the handlebar upper holder,
and then tighten the bolts on the
rear side.
Steering nut wrench: YU-33975/90890-01403
Steering nut wrench: YU-33975/90890-01403
Steering ring nut (initial
tightening): 38 Nm (3.8 m•kg, 27
ft•lb)
Steering ring nut (final
tightening):7 Nm (0.7 m•kg, 5.1
ft•lb)
Steering stem nut: 145 Nm (14.5 m•kg, 105
ft•lb)
Handlebar upper holder: 28 Nm (2.8 m•kg, 20
ft•lb)
Pinch bolt (upper brack-
et): 21 Nm (2.1 m•kg, 15
ft•lb)
Number plate:
7 Nm (0.7 m•kg, 5.1
ft•lb)