radiator cap YAMAHA YZ250F 2015 Owners Manual

DESCRIPTION
1-4
EAS1SM5009
DESCRIPTION
TIP
Designs and specifications of the vehicle are subject to change without notice. Therefore, please
note that the descriptions in this manual may be different from those for the vehicle you have pur-
chased.1. Clutch lever 10. Coolant drain bolt
2. Front brake lever 11. Rear brake pedal
3. Throttle grip 12. Air filter
4. Radiator cap 13. Drive chain
5. Fuel tank cap 14. Shift pedal
6. Engine stop switch 15. Oil level check window
7. Fuel tank 16. Starter knob/idle screw
8. Kickstarter lever 17. Front fork
9. Radiator
2 1
6
78 954 3
11 10 17 16 15 14 1312

SPECIAL TOOLS
1-16
Radiator cap tester
90890-01325
Mityvac cooling system tester
kit
YU-24460-AThis tool is used to check the
radiator and the radiator cap.
Radiator cap tester adapter
90890-01352
Pressure tester adapter
YU-33984This tool is used to check the
radiator and the radiator cap.
Steering nut wrench
90890-01403
Exhaust flange nut wrench
YU-A9472This tool is used to remove or
tighten the steering nut.
Cap bolt wrench
90890-01500
YM-01500This tool is used to remove or
tighten the base valve.
Cap bolt ring wrench
90890-01501
YM-01501This tool is used to loosen or
tighten the damper assem-
bly.
Fork seal driver
90890-01502
YM-A0948This tool is used to install the
oil seal of the front fork.
Spoke nipple wrench (6–7)
90890-01521
YM-01521This tool is used to tighten the
spoke. Tool name/Part number How to use Illustration

ENGINE SPECIFICATIONS
2-2
EAS1SM5054
ENGINE SPECIFICATIONS
Engine
Engine type Liquid cooled 4-stroke, DOHC
Displacement 250 cm
3
Cylinder arrangement Single cylinder
Bore  stroke 77.0  53.6 mm (3.0  2.1 in)
Compression ratio 13.5:1
Starting system Kickstarter
Fuel
Recommended fuel Premium unleaded gasoline only
Fuel tank capacity 7.5 L (1.98 US gal, 1.65 Imp.gal)
Engine oil
Lubrication system Wet sump
Recommended brand YAMALUBE
Type SAE 10W-30, SAE 10W-40, SAE 10W-50,
SAE 15W-40, SAE 20W-40 or SAE 20W-50
Recommended oil grade API service SG type or higher, JASO standard
MA
Engine oil quantity
Quantity (disassembled) 0.90 L (0.95 US qt, 0.79 Imp.qt)
With oil filter element replacement 0.73 L (0.77 US qt, 0.64 Imp.qt)
Without oil filter element replacement 0.71 L (0.75 US qt, 0.62 Imp.qt)
Oil filter
Oil filter type Paper
Oil pump
Oil pump type Trochoid
Inner-rotor-to-outer-rotor-tip clearance Less than 0.150 mm (0.0059 in)
Limit 0.20 mm (0.0079 in)
Outer-rotor-to-oil-pump-housing clearance 0.13–0.18 mm (0.0051–0.0071 in)
Limit 0.24 mm (0.0094 in)
Oil-pump-housing-to-inner-and-outer-rotor
clearance 0.06–0.11 mm (0.0024–0.0043 in)
Limit 0.17 mm (0.0067 in)
Cooling system
Radiator capacity (including all routes) 1.00 L (1.06 US qt, 0.88 Imp.qt)
Radiator capacity 0.58 L (0.61 US qt, 0.51 Imp.qt)
Radiator cap opening pressure 108–137 kPa (1.08–1.37 kg/cm
2, 15.7–19.9
psi)
Radiator core
Width 112.6 mm (4.43 in)
Height 235.0 mm (9.25 in)
Depth 28.0 mm (1.10 in)
Water pump
Water pump type Single suction centrifugal pump
Spark plug
Manufacturer/model NGK/LMAR8G
Spark plug gap 0.7–0.8 mm (0.028–0.031 in)

TIGHTENING TORQUES
2-13
EAS1SM5058ENGINE TIGHTENING TORQUES
TIP
- marked portion shall be checked for torque tightening after break-in or before each race.
ITEMThread
sizeQ’ty TIGHTENING TORQUES Remarks
Camshaft cap bolt
M6 8 10 Nm (1.0 m·kgf, 7.2 ft·lbf)
Cylinder head blind plug
M12 1 28 Nm (2.8 m·kgf, 20 ft·lbf)
Spark plug
M10 1 13 Nm (1.3 m·kgf, 9.4 ft·lbf)
Cylinder head stud bolt
M6 2 7 Nm (0.7 m·kgf, 5.1 ft·lbf)
Cylinder head stud bolt (exhaust
pipe)M8 2 15 Nm (1.5 m·kgf, 11 ft·lbf)
Cylinder head bolts
M9 4 33 Nm (3.3 m·kgf, 24 ft·lbf)
Cylinder head nuts
M6 2 10 Nm (1.0 m·kgf, 7.2 ft·lbf)
Cylinder head cover bolt
M6 2 10 Nm (1.0 m·kgf, 7.2 ft·lbf)
Cylinder bolt
M6 1 10 Nm (1.0 m·kgf, 7.2 ft·lbf)
Oil pressure check bolt
M6 1 10 Nm (1.0 m·kgf, 7.2 ft·lbf)
Balancer weight plate screw
M6 2 10 Nm (1.0 m·kgf, 7.2 ft·lbf)
Balancer driven gear nut M14 1 50 Nm (5.0 m·kgf, 36 ft·lbf)
Balancer nut M10 1 38 Nm (3.8 m·kgf, 27 ft·lbf)
Timing chain guide stopper plate
(exhaust side)M6 1 10 Nm (1.0 m·kgf, 7.2 ft·lbf)
Timing chain tensioner cap bolt
M6 1 6 Nm (0.6 m·kgf, 4.3 ft·lbf)
Timing chain tensioner bolt
M6 2 10 Nm (1.0 m·kgf, 7.2 ft·lbf)
Coolant drain bolt
M6 1 10 Nm (1.0 m·kgf, 7.2 ft·lbf)
Radiator hose clamp screw
M6 8 1.5 Nm (0.15 m·kgf, 1.1 ft·lbf)
Radiator bolt
M6 4 10 Nm (1.0 m·kgf, 7.2 ft·lbf)
Radiator pipe bolt
M6 1 10 Nm (1.0 m·kgf, 7.2 ft·lbf)
Radiator pipe joint bolt
M6 1 10 Nm (1.0 m·kgf, 7.2 ft·lbf)
Water pump housing cover bolt
M6 4 10 Nm (1.0 m·kgf, 7.2 ft·lbf)
Oil pump bolt
M5 2 5 Nm (0.5 m·kgf, 3.6 ft·lbf)
Oil pump cover screw
M4 1 2.0 Nm (0.20 m·kgf, 1.4 ft·lbf)
Oil strainer bolt
M6 1 10 Nm (1.0 m·kgf, 7.2 ft·lbf)
Throttle cable cover bolt
M5 1 3.5 Nm (0.35 m·kgf, 2.5 ft·lbf)
Throttle body joint bolt
M6 2 10 Nm (1.0 m·kgf, 7.2 ft·lbf)
Throttle body joint clamp bolt
M5 1 3.0 Nm (0.30 m·kgf, 2.2 ft·lbf)
Air filter joint clamp bolt
M4 1 3.5 Nm (0.35 m·kgf, 2.5 ft·lbf)
Air filter case bolt M6 3 7 Nm (0.7 m·kgf, 5.1 ft·lbf)
Air filter bolt M6 1 2.0 Nm (0.20 m·kgf, 1.4 ft·lbf)
Air filter guide holder screw
M5 8 2.5 Nm (0.25 m·kgf, 1.8 ft·lbf)
LT
M
LT
LT
LT

TIGHTENING TORQUES
2-18
TIP
Lower ring nut
1. First, tighten the lower ring nut approximately 38 Nm (3.8 m·kgf, 27 ft·lbf) by using the steering nut
wrench, then loosen the lower ring nut one turn.
2. Retighten the lower ring nut 7 Nm (0.7 m·kgf, 5.1 ft·lbf).Drive chain tensioner bolt (lower
side)M8 1 16 Nm (1.6 m·kgf, 12 ft·lbf)
Drive chain support bolt M6 1 7 Nm (0.7 m·kgf, 5.1 ft·lbf)
Drive chain support nut M6 2 7 Nm (0.7 m·kgf, 5.1 ft·lbf)
Drive chain guide bolt M5 3 4.0 Nm (0.40 m·kgf, 2.9 ft·lbf)
Rear frame and left cover bolt M6 2 7 Nm (0.7 m·kgf, 5.1 ft·lbf)
Fuel tank bolt (front side) M6 2 7 Nm (0.7 m·kgf, 5.1 ft·lbf)
Fuel tank bolt (rear side) M6 1 9 Nm (0.9 m·kgf, 6.5 ft·lbf)
Fuel tank bracket bolt (front side) M6 4 7 Nm (0.7 m·kgf, 5.1 ft·lbf)
Fuel tank bracket bolt (rear side) M6 2 7 Nm (0.7 m·kgf, 5.1 ft·lbf)
Fuel pump bolt M5 6 4.0 Nm (0.40 m·kgf, 2.9 ft·lbf)
Fuel inlet pipe screw M5 2 3.4 Nm (0.34 m·kgf, 2.5 ft·lbf)
Fuel tank cap cover bolt M6 2 4.0 Nm (0.40 m·kgf, 2.9 ft·lbf)
Seat set bracket and fuel tank screw M6 1 7 Nm (0.7 m·kgf, 5.1 ft·lbf)
Seat bolt M8 2 22 Nm (2.2 m·kgf, 16 ft·lbf)
Left side cover bolt M6 1 7 Nm (0.7 m·kgf, 5.1 ft·lbf)
Right side cover bolt M6 2 7 Nm (0.7 m·kgf, 5.1 ft·lbf)
Frame and air scoop bolt M6 2 7 Nm (0.7 m·kgf, 5.1 ft·lbf)
Fuel tank and air scoop bolt M6 2 7 Nm (0.7 m·kgf, 5.1 ft·lbf)
Radiator guard and air scoop bolt M6 4 7 Nm (0.7 m·kgf, 5.1 ft·lbf)
Front fender bolt M6 4 10 Nm (1.0 m·kgf, 7.2 ft·lbf)
Rear fender bolt (front side) M6 4 7 Nm (0.7 m·kgf, 5.1 ft·lbf)
Rear fender bolt (rear side) M6 2 16 Nm (1.6 m·kgf, 12 ft·lbf)
Mud flap screw — 2 1.3 Nm (0.13 m·kgf, 0.94 ft·lbf)
Number plate bolt M6 1 7 Nm (0.7 m·kgf, 5.1 ft·lbf)ITEMThread
sizeQ’ty TIGHTENING TORQUES Remarks

CABLE ROUTING DIAGRAM
2-38
1. Main harness
2. Radiator
3. Throttle position sensor lead
4. Joint coupler
5. Intake air temperature sensor lead
6. Intake air pressure sensor lead
7. Frame
8. Fuel hose
9. High tension cord
10. Spark plug cap
11. Cylinder head cover
12. Sub-wire harness
13. Injector coupler
14. Injector lead
15. Throttle body
16. Air filter case
17. ECU
18. Sub-wire harness coupler
A. Fix the main harness by the plastic clamp, and in-
sert the projection of the plastic clamp into the
hole in the sheet metal of the radiator.
B. Insert the projection of the main harness into the
hole in the frame.
C. To the sub-wire harness
D. Pass the high tension cord above the fuel hose.
E. ±10°
F. Install the spark plug cap with this facing the right
of the vehicle.
G. Push the spark plug cap home, where there shall
be no gap between it and the cylinder head cover.
H. Pass the injector lead to the top of the vehicle be-
yond the fuel hose.
I. Insert the coupler of the sub-wire harness into the
rib of the air filter case.
J. Pass the sub-wire harness between the ECU and
the air filter case.

3
PERIODIC CHECKS AND ADJUSTMENTS
MAINTENANCE INTERVALS.......................................................................... 3-1
MAINTENANCE INTERVALS .................................................................... 3-1
PRE-OPERATION INSPECTION AND MAINTENANCE................................. 3-7
GENERAL INSPECTION AND MAINTENANCE........................................ 3-7
ENGINE............................................................................................................ 3-8
CHECKING THE COOLANT LEVEL .......................................................... 3-8
CHECKING THE COOLING SYSTEM ....................................................... 3-8
CHANGING THE COOLANT...................................................................... 3-8
CHECKING THE RADIATOR CAP ............................................................ 3-9
CHECKING THE RADIATOR CAP OPENING PRESSURE ...................... 3-9
CHECKING THE COOLANT CIRCULATORY SYSTEM FOR LEAKS .... 3-10
ADJUSTING THE CLUTCH LEVER POSITION ...................................... 3-10
ADJUSTING THE CLUTCH LEVER FREE PLAY .................................... 3-10
ADJUSTING THE THROTTLE GRIP FREE PLAY .................................. 3-11
LUBRICATING THE THROTTLE CABLE ................................................ 3-12
CLEANING THE AIR FILTER ELEMENT................................................. 3-12
CHECKING THE THROTTLE BODY JOINT ............................................ 3-13
CHECKING THE BREATHER HOSES .................................................... 3-13
CHECKING THE EXHAUST SYSTEM..................................................... 3-13
CHECKING THE FUEL LINE ................................................................... 3-14
CHECKING THE ENGINE OIL LEVEL..................................................... 3-14
CHANGING THE ENGINE OIL ................................................................ 3-15
ADJUSTING THE ENGINE IDLING SPEED ............................................ 3-16
ADJUSTING THE VALVE CLEARANCE ................................................. 3-17
CHASSIS........................................................................................................ 3-21
BLEEDING THE BRAKE SYSTEM .......................................................... 3-21
CHECKING THE BRAKE HOSE .............................................................. 3-22
ADJUSTING THE FRONT BRAKE .......................................................... 3-22
ADJUSTING THE REAR BRAKE ............................................................. 3-23
CHECKING THE FRONT BRAKE PADS ................................................. 3-23
CHECKING THE REAR BRAKE PADS ................................................... 3-25
CHECKING THE REAR BRAKE PAD INSULATOR ................................ 3-26
CHECKING THE BRAKE FLUID LEVEL.................................................. 3-26
ADJUSTING THE DRIVE CHAIN SLACK ................................................ 3-27
CHECKING THE FRONT FORK LEGS ................................................... 3-28
CHECKING THE FRONT FORK PROTECTOR GUIDE .......................... 3-28
CLEANING THE FRONT FORK OIL SEAL AND DUST SEAL ................ 3-28
AIR BLEEDING FROM FRONT FORK .................................................... 3-28
ADJUSTING THE FRONT FORK LEGS .................................................. 3-29
CHECKING THE SWINGARM OPERATION ........................................... 3-30
CHECKING THE REAR SUSPENSION ................................................... 3-30
ADJUSTING THE REAR SHOCK ABSORBER ASSEMBLY ................... 3-30
CHECKING THE TIRES ........................................................................... 3-32
CHECKING AND TIGHTENING THE SPOKES ....................................... 3-32
CHECKING THE WHEELS ...................................................................... 3-33

MAINTENANCE INTERVALS
3-3
NUT (ROTOR)
Retighten Check for tightening torques.
EXHAUST PIPE, SI-
LENCER, PROTEC-
TOR
Inspect and re-
tightenCheck for exhaust leaks, and
tightening torques.
Clean
Replace fiver ** When the exhaust sound be-
comes louder or when a per-
formance drop is felt.
CRANKSHAFT
Inspect and clean
THROTTLE BODY
Inspect
AIR FILTER
Clean and lubri-
cateUse foam air-filter oil or equiv-
alent oil.
Replace
SPARK PLUG
Inspect and clean Check the electrodes and the
terminals for wear.
Replace
COOLING SYSTEM
Check coolant lev-
el and leakage
Check radiator cap
operationUse the radiator cap tester for
a checkup.
Check radiator cap
attached
Change the cool-
antEvery two years
Inspect hoses
ENGINE GUARD
Replace Breakage
FRAME
Clean and inspectITEMAfter
break-
inEvery
race
(about
2.5
hours)Every
third
(about
7.5
hours)Every
fifth
(about
12.5
hours)As re-
quiredRemarks

PRE-OPERATION INSPECTION AND MAINTENANCE
3-7
EAS1SM5068
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.
EAS1SM5069GENERAL INSPECTION AND MAINTENANCE
TIP
Perform usual maintenance enough so that, in the race course, a confirmation of that and simple set-
ting adjustments may only be left, in order to get enough time to use effectively.ITEM inspect Page
CoolantCheck that coolant is filled up to the radiator cap.
Check the cooling system for leakage.3-8 – 10
FuelCheck that a fresh gasoline is filled in the fuel tank.
Check the fuel line for leakage.1-22
Engine oilCheck that the oil level is correct. Check the crank-
case and oil line for leakage.3-14 – 16
Gear shifter and clutchCheck that gears can be shifted correctly in order and
that the clutch operates smoothly.3-10 – 11
Throttle grip/HousingCheck that the throttle grip operation and free play
are correctly adjusted. Lubricate the throttle grip and
housing, if necessary.3-11 – 12
BrakesCheck the play of front brake and effect of front and
rear brake.3-21 – 27
Drive chainCheck drive chain slack and alignment. Check that
the drive chain is lubricated properly.3-27
4-64 – 65
WheelsCheck for excessive wear and tire pressure. Check
for loose spokes and have no excessive play.3-32 – 33
SteeringCheck that the handlebar can be turned smoothly and
have no excessive play.3-33 – 34
Front forks and rear
shock absorberCheck that they operate smoothly and there is no oil
leakage.3-28 – 32
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.3-13 – 14
Rear wheel sprocketCheck that the rear wheel sprocket tightening bolt is
not loose.4-8 – 9
Lubrication Check for smooth operation. Lubricate if necessary. 3-12, 3-34
Bolts and nutsCheck the chassis and engine for loose bolts and
nuts.1-25 – 26
Lead connectorsCheck that the AC magneto, ECU and ignition coil are
connected tightly.1-12 – 14
SettingsIs the machine set suitably for the condition of the rac-
ing course and weather or by taking into account the
results of test runs before racing? Are inspection and
maintenance completely done?10-1 – 8

ENGINE
3-8
EAS1SM5070
ENGINE
EAS1SM5071CHECKING THE COOLANT LEVELEWA1DX1003
WARNING
If coolant seems hot, do not remove the ra-
diator cap.
1. Stand the vehicle upright on a level surface.
2. Remove:
• Radiator cap “1”
3. Check:
• Coolant level
Maximum level “a” or below  Add coolant
up to the maximum level.
ECA1DX1004
NOTICE
• Adding water instead of coolant lowers the
antifreeze content. If, therefore, water is
used instead of coolant, check, and if nec-
essary, adjust the antifreeze concentra-
tion.
• Use only distilled water. However, if dis-
tilled water is not available, soft water may
be used.
4. Start the engine, warm this up for several
minutes, and then stop it.
5. Check:
• Coolant level
TIP
Before checking the coolant level, wait a few
minutes until the coolant has settled.
EAS1SM5072CHECKING THE COOLING SYSTEM
1. Remove:
• Seat
• Side cover (left/right)
• Air scoop (left/right)
Refer to “GENERAL CHASSIS” on page 4-
1.
• Air filter case cover
Refer to “THROTTLE BODY” on page 7-5.
2. Check:
•RADIATOR
• Radiator hoses
Crack/damage  Replace.
Refer to “RADIATOR” on page 6-1.
3. Install:
• Air filter case cover
Refer to “THROTTLE BODY” on page 7-5.
• Air scoop (left/right)
• Seat
• Side cover (left/right)
Refer to “GENERAL CHASSIS” on page 4-
1.
EAS1SM5073CHANGING THE COOLANTEWA1DX1004
WARNING
If coolant seems hot, do not remove the ra-
diator cap.
1. Place a container under the engine.
2. Remove:
• Coolant drain bolt “1”
3. Remove:
• Radiator cap
Slowly loosen the radiator cap to drain cool-
ant.
TIP
When the radiator cap is loosened, coolant will
gush out transversely; therefore, bring the con-
tainer near to the outlet.
4. Thoroughly flush the cooling system with
clean tap water.
1. Radiator
1