2015 YAMAHA WR 250F engine

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
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6 7
8 9 10A
BC
4

IMPORTANT INFORMATION
1-9
EAS20180
IMPORTANT INFORMATION
EAS2GB2022PREPARATION FOR REMOVAL AND DIS-
ASSEMBLY
1. Before the jobs, completely remove mud,
dust, and the like in order to prevent the en-
try of them into the inside during the jobs.
• Before cleaning with high-pressure water of
washers, cover the following parts.
Air duct
Silencer exhaust port
Drain hole on the cylinder head (right side)
Hole under the water pump housing
2. Use proper special tools and equipment.
See “SPECIAL TOOLS”.
3. During disassembly, check and measure the
required parts, and make a record of them
so that you may refer to the record when in-
stalling them. Moreover, arrange gears, cyl-
inders, pistons, and other parts for each
section so as not to confuse or lose them.4. During disassembly, clean each of the parts,
and store them in trays for each section.
5. Flammable. Keep servicing areas away
from any source of fire.
6. During servicing, take special care not to re-
ceive an injury or a burn on the engine, the
exhaust pipe, the silencer, or the like.
7. If coolant is left adhered to the chassis, paint
and plating will be damaged. Therefore,
rinse it out with water in good time.
EWA
WARNING
Coolant is potentially harmful and should
be handled with special care.
• If it enters your eyes, wash it away with wa-
ter enough and then get medical attention
• If it splashes on your skin or clothes,
quickly wash it away with water and then
with soapy water.
• If it is swallowed, immediately induce vom-
iting and get medical attention.
EAS2GB2023REPLACEMENT PARTS
Make sure that the parts and grease or oil to be
used for repair of the vehicle, including periodic
replacement parts, are new YAMAHA genuine
parts and recommended parts.
Do not use any used parts, because these may
not be genuine though they have similar ap-
pearances or because the quality may be
changed by aging.

IMPORTANT INFORMATION
1-10
EAS2GB2024GASKETS, OIL SEALS AND O-RINGS
1. When overhauling the engine, replace all
gaskets and O-rings. All gasket surfaces, oil
seal lips, and O-rings must be cleaned so
that there may be no dust on them.
2. During assembly, always apply proper oil to
bearings and proper grease to oil seal lips
before installation.
EAS2GB2025LOCK WASHERS/PLATES AND COTTER
PINS
After removal, replace lock washers/plates “1”
and cotter pins with new ones. After the bolt or
nut has been tightened to specification, firmly
bend the lock tabs along a flat of the bolt or nut.
EAS2GB2026BEARINGS AND OIL SEALS
Install bearings “1” and oil seals “2” with their
manufacturer’s marks or size symbols facing
outward. During installation of an oil seal, make
sure that its main lip faces the oil chamber (the
target to be sealed). Before installation, always
apply a light coat of grease to the oil seal lip.
ECA
NOTICE
Do not spin the bearing with compressed air
because this will damage the bearing sur-
faces.
EAS2GB2027CIRCLIPS
When assembling parts, always use new cir-
clips. During installation of a circlip, make sure
that the edge “2” of the circlip “1” is positioned
opposite to the force “3” that the circlip re-
ceives. Install the circlip with its end aligned
with the center of the spline, without opening
the circlip more than necessary.
1. Oil
2. Lip
3. Spring
4. Grease

BASIC SERVICE INFORMATION
1-11
EAS2GB2028
BASIC SERVICE INFORMATION
EAS2GB2029ELECTRICAL SYSTEM
Electrical parts handling
ECA
NOTICE
Never disconnect a battery lead while the
engine is running; otherwise, the electrical
components could be damaged.
ECA
NOTICE
When disconnecting the battery leads from
the battery, be sure to disconnect the nega-
tive battery lead first, then the positive bat-
tery lead. If the positive battery lead is
disconnected first and a tool or similar item
contacts the vehicle, a spark could be gen-
erated, which is extremely dangerous.
TIP
If a battery lead is difficult to disconnect due to
rust on the battery terminal, remove the rust us-
ing hot water.
ECA
NOTICE
Be sure to connect the battery leads to the
correct battery terminals. Reversing the
battery lead connections could damage the
electrical components.
ECA
NOTICE
When connecting the battery leads to the
battery, be sure to connect the positive bat-
tery lead first, then the negative battery
lead. If the negative battery lead is connect-
ed first and a tool or similar item contacts
the vehicle while the positive battery lead is
being connected, a spark could be generat-
ed, which is extremely dangerous.
ECA
NOTICE
Make sure that the multi-function display
goes off after pushing and holding the en-
gine stop switch before disconnecting or
connecting any electrical components.

BASIC SERVICE INFORMATION
1-12
ECA
NOTICE
Handle electrical components with special
care, and do not subject them to strong
shocks.
ECA
NOTICE
Electrical components are very sensitive to
and can be damaged by static electricity.
Therefore, never touch the terminals and be
sure to keep the contacts clean.
TIP
Push and hold the engine stop switch to turn off
the multi-function display when resetting the
ECU (Electronic Control Unit). Disconnect the
starter motor lead of the starter relay, and then
push the starter switch. Be sure to wait for five
seconds or longer before pushing the start
switch after the multi-function display goes off.Checking the electrical system
TIP
Before checking the electrical system, make
sure that the battery voltage is at least 12 V.
ECA
NOTICE
Never insert the tester probes into the cou-
pler terminal slots. Always insert the probes
from the opposite end “a” of the coupler,
taking care not to loosen or damage the
leads.
ECA
NOTICE
For waterproof couplers, never insert the
tester probes directly into the coupler.
When performing any checks using a water-
proof coupler, use the specified test har-
ness or a suitable commercially available
test harness.
a

SPECIAL TOOLS
1-20
Digital tachometer
90890-06760
Digital tachometer
YU-39951-BThis tool is used to measure
the engine speed.
Yamaha bond No. 1215
90890-85505
(Three bond No.1215®)This sealant (Bond) is used
for crankcase mating sur-
face, etc. Tool name/Part number How to use Illustration

CONTROL FUNCTIONS
1-21
EAS2GB2031
CONTROL FUNCTIONS
EAS2GB2032INDICATOR LIGHTS AND WARNING
LIGHTS
1. Engine trouble warning light “ ”
2. Fuel level warning light “ ”
Fuel level warning light “ ”
This warning light comes on when the fuel level
drops below approximately 1.6 L (0.42 US gal,
0.35 Imp.gal). When this occurs, refuel as soon
as possible.
The electrical circuit of the warning light can be
checked by pushing the start switch. The warn-
ing light should come on for a few seconds, and
then go off.
If the warning light does not come on initially
when the start switch is pushed, or if the warn-
ing light remains on, have a Yamaha dealer
check the electrical circuit.
Engine trouble warning light “ ”
This warning light comes on or flashes if a prob-
lem is detected in the electrical circuit monitor-
ing the engine. If this occurs, have a Yamaha
dealer check the vehicle.
The electrical circuit of the warning light can be
checked by pushing the start switch. The warn-
ing light should come on for a few seconds, and
then go off.
If the warning light does not come on initially
when the start switch is pushed, or if the warn-
ing light remains on, have a Yamaha dealer
check the electrical circuit.
EAS2GB2033ENGINE STOP SWITCH
The engine stop switch “1” is located on the left
handlebar. Continue pushing the engine stop
switch till the engine comes to a stop.
After the engine stops, the multi-function dis-
play will go off and the power supply to the ECU
(Electronic Control Unit) will be cut off if the en-
gine stop switch is pushed and held.
TIP
The multi-function display will go off after one
minute if the engine stop switch is not pushed.
EAS2GB2034START SWITCH
The start switch “1” is located on the right han-
dlebar. Push this switch to crank the engine
with the starter.
EAS2GB2035CLUTCH LEVER
The clutch lever “1” is located on the left han-
dlebar. The clutch lever disengages or engag-
es the clutch.
Pull the clutch lever toward the handlebar to
disengage the clutch, and release the lever to
engage the clutch.
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CONTROL FUNCTIONS
1-22
EAS2GB2036SHIFT PEDAL
The shift pedal “1” has adopted a method of 1
down & 5 ups (press-down & kick-ups).
Press it down for N (neutral) to 1st, and kick it
up for 2nd to 6th.
Recommended shift points
The recommended shift points during accelera-
tion and deceleration are shown in the table be-
low.
EAS2GB2037KICKSTARTER LEVER
The kickstarter lever “1” is in the right of the
chassis.
To start the engine, pull out and push down the
kickstarter lever with your foot.
EAS2GB2038
THROTTLE GRIP
The throttle grip “1” is located on the right han-
dlebar. The throttle grip accelerates or deceler-
ates the engine. For acceleration, turn the grip
toward you; for deceleration, turn it away from
you.
EAS2GB2039FRONT BRAKE LEVER
The front brake lever “1” is located on the right
handlebar. Pull it toward the handlebar to acti-
vate the front brake.
EAS2GB2040REAR BRAKE PEDAL
The rear brake pedal “1” is in the right of the
chassis. Press down on the brake pedal to ac-
tivate the rear brake. Shift up points
1st  2nd: 20 km/h (12 mi/h)
2nd  3rd: 30 km/h (19 mi/h)
3rd  4th: 40 km/h (25 mi/h)
4th  5th: 50 km/h (31 mi/h)
5th  6th: 60 km/h (37 mi/h)
Shift down points
6th  5th: 45 km/h (28 mi/h)
5th  4th: 35 km/h (22 mi/h)
4th  3rd: 25 km/h (16 mi/h)
3rd  2nd: 25 km/h (16 mi/h)
2nd  1st: 25 km/h (16 mi/h)
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