fuel pressure YAMAHA WR 250F 2015 Owners Manual

FEATURES
1-6
EAS20170
FEATURES
EAS2GB2014OUTLINE OF THE FI SYSTEM
The main function of a fuel supply system is to provide fuel to the combustion chamber at the opti-
mum air-fuel ratio in accordance with the engine operating conditions and the atmospheric tempera-
ture. In the conventional carburetor system, the air-fuel ratio of the mixture to be supplied to the
combustion chamber is determined by the amount of intake air and fuel that is measured on the basis
of the jets to be used in the carburetor.
Despite the same amount of intake air, the fuel amount requirement varies with the engine operating
conditions (acceleration, deceleration, and operation under a heavy load). The carburetor that mea-
sures fuel through the use of jets are provided with various auxiliary devices, so that the optimum air
fuel ratio can be obtained to accommodate frequent changes in the operating conditions of the en-
gine. This model has adopted an electronically controlled fuel injection (FI) system, in place of the
conventional carburetor system. This system can obtain the optimum air-fuel ratio required by the
engine at all times by using a microprocessor that regulates the fuel injection amount according to
the engine operating conditions detected by various sensors.
1. Fuel injector
2. Throttle position sensor
3. Intake air pressure sensor
4. Engine trouble warning light
5. Intake air temperature sensor
6. ECU
7. Fuel pump
8. Battery
9. Lean angle sensor
10.Crankshaft position sensor
11.Coolant temperature sensor
12.Ignition coil
13.Speed sensor
748
9 10 116 5 123
12
13

FEATURES
1-7
EAS2GB2015FI SYSTEM
The fuel pump delivers fuel to the fuel injector via the fuel filter. The pressure regulator maintains the
fuel pressure that is applied to the fuel injector at only 324 kPa (3.24 kgf/cm
2, 47.0 psi). Accordingly,
when the energizing signal from the ECU energizes the fuel injector, the fuel passage opens, causing
the fuel to be injected into the intake manifold only during the time the passage remains open. There-
fore, the longer the length of time the fuel injector is energized (injection duration), the greater the
volume of fuel that is supplied. Conversely, the shorter the length of time the fuel injector is energized
(injection duration), the lesser the volume of fuel that is supplied.
The injection duration and the injection timing are controlled by the ECU. Signals input from the throt-
tle position sensor, the coolant temperature sensor, the crankshaft position sensor, the intake air
pressure sensor, and the intake air temperature sensor enable the ECU to determine the injection
duration. The injection timing is determined through the signals from the crankshaft position sensor.
As a result, the volume of fuel that is required by the engine can be supplied at all times in accordance
with the driving conditions.
1. Fuel pump
2. Fuel injector
3. ECU
4. Throttle position sensor
5. Coolant temperature sensor
6. Crankshaft position sensor
7. Intake air pressure sensor
8. Throttle body
9. Intake air temperature sensor
10.Air filter case
A. Fuel system
B. Intake system
C. Control system
1
23
5
6 7
8 9 10A
BC
4

SPECIAL TOOLS
1-17
Pocket tester
90890-03112
Analog pocket tester
YU-03112-CThis tool is used to measure
the voltage, current, and re-
sistance of electrical compo-
nents.
Timing light
90890-03141
Timing light
YU-03141This tool is used to measure
the ignition timing.
Pressure gauge
90890-03153
Pressure gauge
YU-03153This tool is used to measure
the fuel pressure.
Fuel pressure adapter
90890-03186
Fuel pressure adapter
YM-03186This tool is used to mount the
pressure gauge.
Test harness S– pressure
sensor (3P)
90890-03207
Test harness S– pressure
sensor (3P)
YU-03207This tool is used to check the
throttle position sensor input
voltage.
Test harness– lean angle
sensor (6P)
90890-03209
Test harness– lean angle
sensor (6P)This tool is used to check the
lean angle sensor output volt-
age.
FI diagnostic tool sub–lead
90890-03212
FI diagnostic tool sub–lead
YU-03212This tool is used to connect
the Yamaha diagnostic tool
to a battery.
Test harness– speed sensor
5TJ (3P)
90890-03228
Test harness– speed sensor
5TJ (3P)
YU-03228This tool is used to check the
speed sensor output voltage.
Yamaha diagnostic tool
90890-03231
Yamaha diagnostic tool (US)
90890-03234This tool is used to check er-
ror codes or carry out self-di-
agnosis. Tool name/Part number How to use Illustration

MAINTENANCE AFTER BREAK-IN
1-35
EAS2GB2057
MAINTENANCE AFTER BREAK-IN
After a break-in, perform careful maintenance
to get ready for the next practice or race.
Refer to “PRE-OPERATION INSPECTION
AND MAINTENANCE” on page 3-9.
EAS2GB2058MAJOR MAINTENANCE
1. For the engine
• Leaks around the engine
Check for pressure leaks from the cylinder
head or the cylinder, oil leaks from the
crankcase or the case cover, leaks from the
coolant system, and other leaks.
• Check that the valve, the cylinder head, the
cylinder, the piston, and the piston ring fit
one another, and that contact between the
valve and the cylinder head, and that be-
tween the cylinder and the piston are cor-
rect.
• Engine oil change
Drain the oil, and check for dirt and foreign
materials such as metal chips. (If any foreign
material is mixed, disassemble and check
the crankcase.)
Pour the specified amount of the recom-
mended oil.
• AC magneto
Check for looseness in mounted areas of
the rotor and the stator.
Check that the connector is not being dis-
connected.
• Silencer
Check the main body and stay for cracks.
Check for leaks.
• Mounting bolts and nuts
Check for looseness in mounted areas of
parts, as well as engine mounting bolts and
engine brackets.
2. For the chassis
• Check welds and mounted areas of the
frame, the swingarm, the link, the bracket,
and so on, for looseness and cracks.
• Wheel (s)
Check the wheel for runout. Check the
spoke for looseness.
• Brake(s)
Check the brake disc mounting bolt for
looseness.
Check that the reservoir contains the speci-
fied amount of brake fluid. Check for leaks.• Cable
Grease and adjust cables.
•Drive chain
Lubricate the drive chain and adjust its ten-
sion.
• Fuel tank
Clean the inside of the fuel tank. Check for
leaks.
• Suspension
Check for oil leaks in the front fork or the rear
shock absorber. Check that the mounted
conditions are good.
• Sprocket
Check for looseness in the sprocket mount-
ed on the rear wheel.
• Mounting bolts and nuts
Check mounted areas for looseness.
ECA
NOTICE
After a break-in or before each race, always
check the points shown in “TORQUE-
CHECK POINTS” for tightening torques and
retighten them. (Refer to “TORQUE-CHECK
POINTS” on page 1-36.)
• Greasing and oiling
Always grease or oil the specified points.

MOTORCYCLE CARE AND STORAGE
1-38
EAS2GB2060
MOTORCYCLE CARE AND STOR-
AGE
EAS2GB2061CARE
While the open design of a motorcycle reveals
the attractiveness of the technology, it also
makes it more vulnerable. Rust and corrosion
can develop even if high-quality components
are used. A rusty exhaust pipe may go unno-
ticed on a car, however, it detracts from the
overall appearance of a motorcycle. Frequent
and proper care does not only comply with the
terms of the warranty, but it will also keep your
motorcycle looking good, extend its life and op-
timize its performance.
Before cleaning
1. Cover the muffler outlet with a plastic bag af-
ter the engine has cooled down.
2. Make sure that all caps and covers as well
as all electrical couplers and connectors, in-
cluding the spark plug cap, are tightly in-
stalled.
3. Remove extremely stubborn dirt, like oil
burnt onto the crankcase, with a degreasing
agent and a brush, but never apply such
products onto seals, gaskets, sprockets, the
drive chain and wheel axles. Always rinse
the dirt and degreaser off with water.
Cleaning
ECA
NOTICE
• Avoid using strong acidic wheel cleaners,
especially on spoked wheels. If such prod-
ucts are used on hard-to-remove dirt, do
not leave the cleaner on the affected area
any longer than instructed. Also, thor-
oughly rinse the area off with water, imme-
diately dry it, and then apply a corrosion
protection spray.
• Improper cleaning can damage plastic
parts (such as cowlings, panels, wind-
shields, headlight lenses, meter lenses,
etc.) and the mufflers. Use only a soft,
clean cloth or sponge with water to clean
plastic. However, if the plastic parts can-
not be thoroughly cleaned with water, di-
luted mild detergent with water may be
used. Be sure to rinse off any detergent
residue using plenty of water, as it is
harmful to plastic parts.• Do not use any harsh chemical products
on plastic parts. Be sure to avoid using
cloths or sponges which have been in con-
tact with strong or abrasive cleaning prod-
ucts, solvent or thinner, fuel (gasoline),
rust removers or inhibitors, brake fluid,
antifreeze or electrolyte.
• Do not use high-pressure washers or
steam-jet cleaners since they cause water
seepage and deterioration in the following
areas: seals (of wheel and swingarm bear-
ings, fork and brakes), electric compo-
nents (couplers, connectors, instruments,
switches and lights), breather hoses and
vents.
• For motorcycles equipped with a wind-
shield: Do not use strong cleaners or hard
sponges as they will cause dulling or
scratching. Some cleaning compounds for
plastic may leave scratches on the wind-
shield. Test the product on a small hidden
part of the windshield to make sure that it
does not leave any marks. If the wind-
shield is scratched, use a quality plastic
polishing compound after washing.
After normal use
Remove dirt with warm water, a mild detergent,
and a soft, clean sponge, and then rinse thor-
oughly with clean water. Use a toothbrush or
bottlebrush for hard-to-reach areas. Stubborn
dirt and insects will come off more easily if the
area is covered with a wet cloth for a few min-
utes before cleaning.
After riding in the rain, near the sea or on salt-
sprayed roads
Since sea salt or salt sprayed on roads during
winter are extremely corrosive in combination
with water, carry out the following steps after
each ride in the rain, near the sea or on salt-
sprayed roads.
TIP
Salt sprayed on roads in the winter may remain
well into spring.
1. Clean the motorcycle with cold water and a
mild detergent, after the engine has cooled
down.
NOTICE: Do not use warm water since it
increases the corrosive action of the salt.

ENGINE SPECIFICATIONS
2-2
EAS2GB2064
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 Electric starter and kickstarter
Fuel
Recommended fuel Premium unleaded gasoline only
Fuel tank capacity 7.5 L (1.98 US gal, 1.65 Imp.gal)
Fuel reserve amount 1.6 L (0.42 US gal, 0.35 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 engine oil grade API service SG type or higher, JASO standard
MA
Engine oil quantity
Quantity (disassembled) 1.10 L (1.16 US qt, 0.97 Imp.qt)
Without oil filter element replacement 0.83 L (0.88 US qt, 0.73 Imp.qt)
With oil filter element replacement 0.85 L (0.90 US qt, 0.75 Imp.qt)
Oil filter
Oil filter type Paper
Bypass valve opening pressure 40.0–80.0 kPa (0.40–0.80 kgf/cm
2,
5.8–11.6 psi)
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 0.56 L (0.60 US qt, 0.50 Imp.qt)
Radiator cap opening pressure 107.9–137.3 kPa (1.08–1.37 kg/cm
2,
15.6–19.9 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)

ENGINE SPECIFICATIONS
2-7
Fuel pump
Pump type Electrical
Fuel injector
Model/quantity 30NA-FZ31/1
Resistance 12 
Throttle body
Type/quantity 30RA-A95R/1
ID mark 2GB1 00
Fuel line pressure at idling 324.0 kPa (3.24 kgf/cm
2, 47.0 psi)
Throttle position sensor
Resistance 6.30 k
Output voltage (at idle) 0.5 V
Fuel injection sensor
Crankshaft position sensor resistance 228–342  (Gy–B)
Intake air pressure sensor output voltage 3.61–3.67 V at 101.3 kPa (3.61–3.67 V at 1.01
kgf/cm
2, 3.61–3.67 V at 14.7 psi)
Intake air temperature sensor resistance 290–390  at 80 °C (290–390  176 °F)
Coolant temperature sensor resistance 2.51–2.78 k at 20 °C (2.51–2.78 k at 68 °F)
210–221  at 100 °C (210–221  at 212 °F)
Idling condition
Engine idling speed 1900–2100 r/min
CO% 3.0–4.0 % (USA) (CAN)
Intake vacuum 25.3–29.3 kPa (190–220 mmHg, 7.5–8.7 inHg)
(USA) (CAN)
Water temperature 70.0–90.0 °C (158.00–194.00 °F)
Oil temperature 70.0–80.0 °C (158.00–176.00 °F)
Throttle grip free play 3.0–5.0 mm (0.12–0.20 in)

CABLE ROUTING DIAGRAM
2-36
1. Clamp
2. Cylinder head breather hose
3. Throttle position sensor lead
4. Joint coupler
5. Intake air temperature sensor coupler
6. Intake air pressure sensor lead
7. Wire harness
8. Injector lead
9. Throttle body
10. Injector coupler
11. Starter motor lead
12. Plastic band
13. Fuel sender coupler
14. High tension cord
15. Spark plug cap
16. Cylinder head cover
17. Fuel hose
18. Fuel sender
19. Sub-wire harness
20. Crankcase breather hose
21. Radiator breather hose
22. Radiator hose
23. Down tube
24. Starter motor
25. Neutral switch lead
26. AC magneto lead
27. Clutch cable
28. Radiator
29. Air filter case breather hose
30. Breather hose clamp
31. Grommet (high tension cord)
32. ECU
33. Air filter case
34. Sub-wire harness coupler
35. Engine bracket
A. Fix the wire harness, clutch switch lead and start
switch lead by the plastic clamp, and insert the
projection of the plastic clamp into the hole in the
sheet metal of the radiator.
B. Route each lead so that the leads are not pinched
between the tank rail and air filter joint.
C. Insert the projection of the wire harness into the
hole in the frame.
D. Route the cylinder head breather hose without it
crossing the starter motor lead.
E. Pass the cylinder head breather hose between
the throttle cable and rectifier/regulator lead.
F. Connect the sub-wire harness to the wire har-
ness.
G. Pass the high tension cord above the fuel hose.
H. ±10°
I. Install the spark plug cap with this facing the right
of the vehicle.
J. Push the spark plug cap home, where there shall
be no gap between it and the cylinder head cover.
K. Pass the radiator breather hose between the
down tubes.
L. Apply adhesive to the slit and inside of the grom-
met, and then fix the grommet according to the
specified dimensions.
M. Pass the sub-wire harness between the ECU and
the air filter case.
N. Insert the coupler of the sub-wire harness into the
rib of the air filter case.
O. Route the radiator breather hose through be-
tween the radiator hose, down tube and engine
bracket.

CABLE ROUTING DIAGRAM
2-38
1. Cable guide
2. Speed sensor lead
3. Joint coupler
4. Ground lead
5. Throttle position sensor lead
6. Throttle position sensor coupler
7. Radiator breather hose
8. Cylinder head breather hose
9. Crankcase breather hose
10. Radiator hose
11. Fuel hose
12. Engine ground lead
13. Coolant temperature sensor coupler
14. Radiator fan motor lead
15. Intake air pressure sensor coupler
16. Intake air temperature sensor coupler
17. Start switch coupler
18. Radiator fan motor coupler
19. Clutch switch coupler
20. Air filter case
21. Plate
22. Bracket
A. Pass the wire harness under the start switch lead
and clutch switch lead.
B. Insert and fix the joint coupler to the plate. After
fixing it, attach the cover.
C. Pass the throttle position sensor lead to the out-
side of the tension arm (the outside of the vehi-
cle).
D. After connecting the throttle position sensor cou-
pler, attach the cover.
E. Pass the radiator breather hose to the outside of
the tension arm and the throttle position sensor
lead (the outside of the vehicle), and to the inside
of the radiator hose (the side of the vehicle).
F. 45°
G. Install the engine ground lead within a range of
45° from a location where it will not run over the
step difference of the radiator hose joint. Both
sides of the engine ground lead terminal can be
used.
H. Attach the coupler cover to the coolant tempera-
ture sensor coupler.
I. Pass the radiator fan motor lead to the inside of
the tension arm (the side of the vehicle).
J. Install the ground lead terminal between the plate
and the bolt.
K. Fix the ground lead terminal to the detent in the
plate. For the ground lead terminal, either side
will do.
L. Detent

3
PERIODIC CHECKS AND ADJUSTMENTS
PERIODIC MAINTENANCE............................................................................. 3-1
INTRODUCTION ........................................................................................ 3-1
PERIODIC MAINTENANCE CHART FOR THE EMISSION
CONTROL SYSTEM ................................................................................. 3-1
GENERAL MAINTENANCE AND LUBRICATION CHART ........................ 3-2
MAINTENANCE INTERVALS FOR COMPETITION USE ......................... 3-4
PRE-OPERATION INSPECTION AND MAINTENANCE................................. 3-9
GENERAL INSPECTION AND MAINTENANCE........................................ 3-9
ENGINE.......................................................................................................... 3-10
CHECKING THE COOLANT LEVEL ........................................................ 3-10
CHECKING THE COOLING SYSTEM ..................................................... 3-10
CHANGING THE COOLANT.................................................................... 3-10
CHECKING THE RADIATOR CAP .......................................................... 3-11
CHECKING THE RADIATOR CAP OPENING PRESSURE .................... 3-11
CHECKING THE COOLANT CIRCULATORY SYSTEM FOR LEAKS .... 3-12
ADJUSTING THE CLUTCH LEVER FREE PLAY .................................... 3-12
ADJUSTING THE THROTTLE GRIP FREE PLAY .................................. 3-13
LUBRICATING THE THROTTLE CABLE ................................................ 3-13
CLEANING THE AIR FILTER ELEMENT................................................. 3-14
CHECKING THE THROTTLE BODY JOINT ............................................ 3-15
CHECKING THE BREATHER HOSES .................................................... 3-15
CHECKING THE EXHAUST SYSTEM..................................................... 3-15
CHECKING THE FUEL LINE ................................................................... 3-16
CHECKING THE ENGINE OIL LEVEL..................................................... 3-16
CHANGING THE ENGINE OIL ................................................................ 3-17
ADJUSTING THE ENGINE IDLING SPEED ............................................ 3-18
ADJUSTING THE VALVE CLEARANCE ................................................. 3-19
CLEANING THE SPARK ARRESTER ..................................................... 3-23
CHASSIS........................................................................................................ 3-24
BLEEDING THE BRAKE SYSTEM .......................................................... 3-24
CHECKING THE BRAKE HOSE .............................................................. 3-25
ADJUSTING THE FRONT BRAKE .......................................................... 3-25
ADJUSTING THE REAR BRAKE ............................................................. 3-26
CHECKING THE FRONT BRAKE PADS ................................................. 3-26
CHECKING THE REAR BRAKE PADS ................................................... 3-28
CHECKING THE REAR BRAKE PAD INSULATOR ................................ 3-29
CHECKING THE BRAKE FLUID LEVEL.................................................. 3-29
ADJUSTING THE DRIVE CHAIN SLACK ................................................ 3-30
CHECKING THE FRONT FORK LEGS ................................................... 3-31
CHECKING THE FRONT FORK PROTECTOR GUIDE .......................... 3-31
CLEANING THE FRONT FORK OIL SEAL AND DUST SEAL ................ 3-31
AIR BLEEDING FROM FRONT FORK .................................................... 3-31
ADJUSTING THE FRONT FORK LEGS .................................................. 3-32
CHECKING THE SWINGARM OPERATION ........................................... 3-33
CHECKING THE REAR SUSPENSION ................................................... 3-33