2015 YAMAHA WR 250F ECU

EAS2GB2005
SAFETY INFORMATION
THIS MACHINE IS DESIGNED STRICTLY FOR COMPETITION USE, ONLY ON A CLOSED
COURSE. It is illegal for this machine to be operated on any public street, road, or highway. Off-road
use on public lands may also be illegal. Please check local regulations before riding.
• THIS MACHINE IS TO BE OPERATED BY AN EXPERIENCED RIDER ONLY.
Do not attempt to operate this machine at maximum power until you are totally familiar with its char-
acteristics.
• THIS MACHINE IS DESIGNED TO BE RIDDEN BY THE OPERATOR ONLY.
Do not carry passengers on this machine.
• ALWAYS WEAR PROTECTIVE APPAREL.
When operating this machine, always wear an approved helmet with goggles or a face shield. Also
wear heavy boots, gloves, and protective clothing. Always wear proper fitting clothing that will not
be caught in any of the moving parts or controls of the machine.
• ALWAYS MAINTAIN YOUR MACHINE IN PROPER WORKING ORDER.
For safety and reliability, the machine must be properly maintained. Always perform the pre-oper-
ation checks indicated in this manual.
Correcting a mechanical problem before you ride may prevent an accident.
• GASOLINE IS HIGHLY FLAMMABLE.
Always turn off the engine while refueling. Take care to not spill any gasoline on the engine or ex-
haust system. Never refuel in the vicinity of an open flame, or while smoking.
• GASOLINE CAN CAUSE INJURY.
If you should swallow some gasoline, inhale excess gasoline vapors, or allow any gasoline to get
into your eyes, contact a doctor immediately. If any gasoline spills onto your skin or clothing, imme-
diately wash skin areas with soap and water, and change your clothes.
• ONLY OPERATE THE MACHINE IN AN AREA WITH ADEQUATE VENTILATION.
Never start the engine or let it run for any length of time in an enclosed area. Exhaust fumes are
poisonous. These fumes contain carbon monoxide, which by itself is odorless and colorless. Car-
bon monoxide is a dangerous gas which can cause unconsciousness or can be lethal.
• PARK THE MACHINE CAREFULLY; TURN OFF THE ENGINE.
Always turn off the engine if you are going to leave the machine. Do not park the machine on a slope
or soft ground as it may fall over.
• THE ENGINE, EXHAUST PIPE AND MUFFLER WILL BE VERY HOT AFTER THE ENGINE HAS
BEEN RUN.
Be careful not to touch them or to allow any clothing item to contact them during inspection or repair.
• PROPERLY SECURE THE MACHINE BEFORE TRANSPORTING IT.
For safety, drain the gasoline from the fuel tank before transporting the vehicle.

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
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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

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

BASIC SERVICE INFORMATION
1-13
Checking the connections
Check the leads, couplers, and connectors for
stains, rust, moisture, etc.
1. Disconnect:
• Lead
• Coupler
• Connector
ECA
NOTICE
• When disconnecting a coupler, release the
coupler lock, hold both sections of the
coupler, and then disconnect the coupler.
• There are many types of coupler locks;
therefore, be sure to check the type of cou-
pler lock before disconnecting the cou-
pler.
ECA
NOTICE
When disconnecting a connector, do not
pull the leads. Hold both sections of the
connector, and then disconnect the con-
nector.2. Check:
• Lead
• Coupler
• Connector
Moisture  Dry with compressed air.
Rust/stains  Connect and disconnect sev-
eral times.
3. Check:
• All connections
Loose connection  Connect properly.
TIP
• If the pin “1” on the terminal is flattened, bend
it up.
• After disassembling or assembling a coupler,
pull on the leads to make sure that they are in-
stalled securely.
1

BASIC SERVICE INFORMATION
1-14
4. Connect:
• Lead
• Coupler
• Connector
TIP
• When connecting a coupler or connector,
make sure that both terminals are connected
securely.
• Make sure all connections are tight.
5. Check:
• No continuity
TIP
• If there is no continuity, clean the terminals.
• When checking the wire harness, perform
steps (1) to (4).
• As a quick remedy, use a contact revitalizer
available at most part stores.Pocket tester
90890-03112
Analog pocket tester
YU-03112-C

SPECIAL TOOLS
1-18
Valve spring compressor
90890-04019
Valve spring compressor
YM-04019This tool is used to discon-
nect or connect the valve and
the valve spring.
Spacer (crankshaft installer)
90890-04081
Pot spacer
YM-91044This tool is used to install the
crankshaft.
Universal clutch holder
90890-04086
Universal clutch holder
YM-91042This tool is used to hold the
clutch when removing or in-
stalling the clutch boss secur-
ing nut.
Valve guide remover (ø5)
90890-04097
Valve guide remover (5.0
mm)
YM-04097This tool is used to replace
the valve guide.
Valve guide installer (ø5)
90890-04098
Valve guide installer (5.0
mm)
YM-04098This tool is used to replace
the valve guide.
Valve guide reamer (ø5)
90890-04099
Valve guide reamer (5.0 mm)
YM-04099This tool is used to replace
the valve guide. Tool name/Part number How to use Illustration
YM-04019
YM-91044

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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