Yamaha Wr250r 2008 Manual

							 
FEATURES 
1-2 
EAS20170 
FEATURES 
EAS32D1017 
OUTLINE OF THE FI SYSTEM 
The main function of a fuel supply system is to provide fuel to the combustion chamber at the optimum
air-fuel ratio in accordance with the engine operating conditions and the atmospheric temperature. In
the conventional carburetor system, the air-fuel ratio of the mixture that is supplied to the combustion
chamber is created by the volume of the intake air and the fuel that is metered by the jet used in the
respective carburetor.
Despite the same volume of intake air, the fuel volume requirement varies by the engine operating con-
ditions, such as acceleration, deceleration, or operating under a heavy load. Carburetors that meter the
fuel through the use of jets have been provided with various auxiliary devices, so that an optimum
air-fuel ratio can be achieved to accommodate the constant changes in the operating conditions of the
engine.
As the requirements for the engine to deliver more performance and cleaner exhaust gases increase,
it becomes necessary to control the air-fuel ratio in a more precise and finely tuned manner. To accom-
modate this need, this model has adopted an electronically controlled fuel injection (FI) system, in place
of the conventional carburetor system. This system can achieve an optimum air-fuel ratio required by
the engine at all times by using a microprocessor that regulates the fuel injection volume according to
the engine operating conditions detected by various sensors.
The adoption of the FI system has resulted in a highly precise fuel supply, improved engine response,
better fuel economy, and reduced exhaust emissions.
9 1
23
456
78
10
11121314
 
1.  Engine trouble warning light
2. Fuel pump
3. Ignition coil
4. Fuel injector
5.  Throttle position sensor
6.  Intake air pressure sensor 1
7. Battery
8.  Lean angle sensor
9. ECU10.  Intake air temperature sensor
11. EXUP servomotor
12. Speed sensor
13.  Coolant temperature sensor
14.  Crankshaft position sensor 
						

							 
FEATURES 
1-3 
EAS32D1018 
FI SYSTEM 
The fuel pump delivers fuel to the fuel injector via the fuel filter. The pressure regulator is installed in
the fuel rail, and maintains the fuel pressure that is applied to the fuel injector at 245 
–  
255 kPa
(34.8 
– 
36.3 psi) (2.45 
– 
2.55 kg/cm 
2
 
). The fuel injector is operated due to signals from the ECU, and in-
jects fuel into the intake manifold. Since fuel is supplied only for the duration of injection, good fuel
economy is obtained. The injection duration and the injection timing are controlled by the ECU. Signals
that are input from the throttle position sensor, crankshaft position sensor, intake air pressure sensor,
intake temperature sensor and coolant 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
10
9B
8
7
6 5 A
23 C411
 
1. Fuel pump
2. Injector
3. ECU
4.  Throttle position sensor
5.  Coolant temperature sensor
6.  Crankshaft position sensor
7.  Intake air pressure sensor
8. Throttle bodies
9.  Intake air temperature sensor
10. Air filter case
11. Pulsation damperA. Fuel system
B. Intake system
C. Control system 
						

							 
FEATURES 
1-4 
EAS32D1004 
MULTI-FUNCTION DISPLAY
WARNING
 
EWA32D1008  
Be sure to stop the vehicle before making
any setting changes to the multi-function 
display.
NOTE:
 
 
The multi-function display can be set to the ba-
sic mode or the measurement mode. 
 
Tripmeter A will automatically reset to zero
when changing from the basic mode to the 
measurement mode or vice versa.
Basic mode: 
 
a speedometer (which shows the riding speed) 
 
an odometer (which shows the total distance
traveled) 
 
two tripmeters (which show the distance trav-
eled since they were last set to zero) 
 
a fuel reserve tripmeter (which shows the dis-
tance traveled since the fuel level warning light
came on) 
 
a clock 
 
a self-diagnosis deviceMeasurement mode: 
 
a speedometer (which shows the riding speed) 
 
a distance-compensation tripmeter (which
shows the accumulated distance traveled
since set to zero and which can be calibrated
to provide a more accurate tripmeter reading) 
 
a stopwatch (which shows the time that has
been accumulated since the start of stopwatch
measurement) 
 
a self-diagnosis device
NOTE:
 
 
Be sure to turn the key to “ON” before using the
“SELECT 1”, “SELECT 2” and “RESET” but-
tons. 
 
When the key is turned to “ON”, all of the dis-
play segments of the multi-function display will
appear and then disappear, in order to test the
electrical circuit. 
 
To switch the speedometer and odometer/
tripmeter displays between kilometers and
miles, press the “SELECT 2” button until the
display changes after the main switch is turned 
to “ON”.  
Basic mode 
Odometer and tripmeter modes
Push the “SELECT 2” button to switch the dis-
play between the odometer mode and the
tripmeter modes A and B in the following order:
odometer  
→  
 tripmeter A   
→  
 tripmeter B   
→  
 odom-
eter
 
1. “RESET” button
2. “SELECT 1” button
3. “SELECT 2” button
4. Clock/stopwatch
5. Speedometer
6.  Odometer/tripmeter/fuel reserve tripmeter
1. Stopwatch indicator “”
2.  Tripmeter A indicator “”/Distance-com-
pensation tripmeter “”
3.  Tripmeter B indicator “”
1
23
4
5
6
1
32
 
1.  Tripmeter A indicator “”
1.  Tripmeter B indicator “”
1
1 
						

							 
FEATURES 
1-5
NOTE:
 
Indicator “” comes on when tripmeter A is se-
lected, and indicator “” comes on when 
tripmeter B is selected.
If the fuel level warning light comes on, the dis-
play will automatically change to the fuel reserve
tripmeter mode “F” and start counting the dis-
tance traveled from that point. In this case, push
the “SELECT 2” button to switch the display be-
tween the various tripmeter and odometer
modes in the following order:
fuel reserve tripmeter “F”  
→ 
 odometer  
→  
tripmeter A  
→ 
 tripmeter B  
→ 
 fuel reserve
tripmeter “F”
NOTE:
 
The fuel level warning light may not function ac-
curately while riding off road as the fuel level
reading changes due to the movement and incli- 
nation of the vehicle.
If the fuel level warning light comes on while
riding in the measurement mode, change to the
basic mode and push the “SELECT 2” button to
display the fuel reserve tripmeter.
NOTE:
 
To change from the measurement mode to the
basic mode, the stopwatch and the dis- 
tance-compensation tripmeter must be stopped.
To reset a tripmeter, select it by pushing the
“SELECT 2” button, and then push the “RESET”
button for at least one second. If you do not reset
the fuel reserve tripmeter manually, it will reset
itself automatically and the display will return to
the prior mode after refueling and traveling 5 km
(3 mi).
Clock
Turn the key to “ON”.
NOTE:
 
When setting the clock, push the “SELECT 1”
button to increase the digits or “SELECT 2” but-
ton to decrease the digits. Pushing and holding
either button will increase or decrease the digits 
continuously until the button is released.
To set the clock
1. Push the “SELECT 1” button for at least two
seconds.
2. When the hour digits start flashing, push ei-
ther select button to set the hours.
3. Push the “RESET” button, and the minute
digits will start flashing.
4. Push either select button to set the minutes.
5. Push the “RESET” button, and the second
digits will start flashing.
6. Push either select button to set the second
digits to zero.
7. Push the “RESET” button for at least two sec-
onds, and then release it to start the clock.
NOTE:
 
If the “RESET” button is not pushed within 30
seconds, the clock will not be set and will return 
to the prior time.  
Changing from the basic mode to the mea-
surement mode 
With the odometer selected, push the “SELECT
1” button and “SELECT 2” button together for at
least two seconds to change to the measure-
ment mode. 
Changing from the measurement mode to
the basic mode
NOTE:
 
The stopwatch must be stopped before chang- 
ing to the basic mode.
1. Check that the stopwatch is not in operation.
If the stopwatch is in operation, stop it by
pushing the “SELECT 1” button and “SE-
LECT 2” button together.
2. Push the “SELECT 1” button and “SELECT
2” button together for at least two seconds to
change to the basic mode. 
Measurement mode (for the stopwatch) 
When the measurement mode is selected, the
stopwatch is displayed and it can be started
manually or automatically.
Manual start
The manual start is the default setting for the
stopwatch. The stopwatch indicator “” and the
distance-compensation tripmeter indicator “”
will start flashing.
 
1.  Fuel reserve tripmeter “F”
1 
						

							 
FEATURES 
1-6 
1. Push the “RESET” button to start the stop-
watch.
2. Push the “SELECT 1” button and “SELECT
2” button together to stop the stopwatch.
3. To resume stopwatch counting, push the
“SELECT 1” button and “SELECT 2” button
together.
To reset the stopwatch to zero, see “Reset-
ting the distance-compensation tripmeter or
the distance-compensation tripmeter in com-
bination with the stopwatch”.
NOTE:
 
The stopwatch will continue counting when the
vehicle is stopped. To stop and/or resume 
counting, repeat steps 2 and 3.
Auto start
1. Push the “SELECT 1” button for at least two
seconds to set the auto start.
NOTE:
 
When the stopwatch is set to auto start, the stop-
watch indicator “” and the distance-compen-
sation tripmeter indicator “” will start flashing,
and the digits in the display will start scrolling 
from left to right.
2. When the vehicle starts moving, the stop-
watch will start counting.
3. Push the “SELECT 1” button and “SELECT
2” button together to stop the stopwatch.
4. To resume counting, push the “SELECT 1”
button and “SELECT 2” button together
again.
NOTE:
 
The stopwatch will continue counting when the
vehicle is stopped. To stop and/or resume 
counting, repeat steps 3 and 4.  
Measurement mode (for calibrating the dis-
tance-compensation tripmeter’s reading)  
The distance-compensation tripmeter is a fea-
ture intended to provide a more accurate
tripmeter reading for enduro riding. Calibrating
this meter in accordance with the distances
specified on the enduro course map will help fa-
miliarize the rider with the course. In addition,
calibrating the meter may also be necessary
when using tire, wheel, chain sprocket sizes,
etc. other than specified.
Calibrate the distance-compensation tripmeter
as follows.
To increase the reading, push the “SELECT 1”
button. To decrease the reading, push the “SE-
LECT 2” button. Pushing and holding either but-
ton will increase or decrease the reading
continuously until the button is released.
NOTE:
 
Calibrating the reading of the distance-compen-
sation tripmeter is possible regardless of the 
stopwatch operation.  
Resetting the distance-compensation
tripmeter or the distance-compensation
tripmeter in combination with the stop-
watch
NOTE:
 
Resetting can be made only to the dis-
tance-compensation tripmeter or to the dis-
tance-compensation tripmeter in combination 
with the stopwatch.
Resetting the distance-compensation tripmeter
1. Check that the stopwatch measurement is in
operation.
2. Reset the distance-compensation tripmeter
to zero by pushing the “RESET” button for at
least two seconds.
Resetting the distance-compensation tripmeter
in combination with the stopwatch
1. Stop the stopwatch.
2. Reset the distance-compensation tripmeter
and the stopwatch to zero by pushing the
“RESET” button for at least two seconds.  
Self-diagnosis device  
This model is equipped with a self-diagnosis de-
vice for various electrical circuits.
If any of those circuits are defective, the engine
trouble warning light will come on, and then the
display will indicate a two-digit error code.
If the display indicates any error codes, note the
code number, and then check the fuel injection 
						

							 
FEATURES 
1-7 
system. Refer to “FUEL INJECTION SYSTEM”
on page 8-29.
CAUTION:
 
 ECA32D1007 
If the display indicates an error code, the ve-
hicle should be checked as soon as possible 
in order to avoid engine damage. 
1.  Error code display
1 
						

							 
IMPORTANT INFORMATION 
1-8 
EAS20180 
IMPORTANT INFORMATION 
EAS20190 
PREPARATION FOR REMOVAL AND 
DISASSEMBLY 
1. Before removal and disassembly, remove all
dirt, mud, dust and foreign material.
2. Use only the proper tools and cleaning equip-
ment.
Refer to “SPECIAL TOOLS” on page 1-11.
3. When disassembling, always keep mated
parts together. This includes gears, cylin-
ders, pistons and other parts that have been
“mated” through normal wear. Mated parts
must always be reused or replaced as an as-
sembly.
4. During disassembly, clean all of the parts and
place them in trays in the order of disassem-
bly. This will speed up assembly and allow for
the correct installation of all parts.
5. Keep all parts away from any source of fire. 
EAS20200 
REPLACEMENT PARTS 
Use only genuine Yamaha parts for all replace-
ments. Use oil and grease recommended by
Yamaha for all lubrication jobs. Other brands
may be similar in function and appearance, but
inferior in quality. 
EAS20210 
GASKETS, OIL SEALS AND O-RINGS  
1. When overhauling the engine, replace all
gaskets, seals and O-rings. All gasket surfac-
es, oil seal lips and O-rings must be cleaned.
2. During reassembly, properly oil all mating
parts and bearings and lubricate the oil seal
lips with grease. 
EAS20220 
LOCK WASHERS/PLATES AND COTTER 
PINS  
After removal, replace all lock washers/plates
“1” and cotter pins. After the bolt or nut has been
tightened to specification, bend the lock tabs
along a flat of the bolt or nut. 
EAS20230 
BEARINGS AND OIL SEALS  
Install bearings and oil seals so that the manu-
facturer’s marks or numbers are visible. When
installing oil seals “1”, lubricate the oil seal lips
with a light coat of lithium-soap-based grease.
Oil bearings liberally when installing, if appropri-
ate. 
						

							 
IMPORTANT INFORMATION 
1-9
CAUTION:
 
 ECA13300 
Do not spin the bearing with compressed air
because this will damage the bearing surfac- 
es. 
EAS20240 
CIRCLIPS 
Before reassembly, check all circlips carefully
and replace damaged or distorted circlips. Al-
ways replace piston pin clips after one use.
When installing a circlip “1”, make sure the
sharp-edged corner “2” is positioned opposite
the thrust “3” that the circlip receives. 
						

							 
CHECKING THE CONNECTIONS 
1-10 
EAS20250 
CHECKING THE CONNECTIONS 
Check the leads, couplers, and connectors for
stains, rust, moisture, etc.
1. Disconnect: 
 
Lead 
 
Coupler 
 
Connector
2. Check: 
 
Lead 
 
Coupler 
 
Connector
Moisture  
→ 
 Dry with an air blower.
Rust/stains  
→ 
 Connect and disconnect sev-
eral times.
3. Check: 
 
All connections
Loose connection  
→ 
 Connect properly.
NOTE:
 
If the pin “1” on the terminal is flattened, bend it 
up.
4. Connect: 
 
Lead 
 
Coupler 
 
Connector
NOTE:
 
Make sure all connections are tight.
5. Check: 
 
Continuity
(with the pocket tester)
NOTE:
 
 
If there is no continuity, clean the terminals. 
 
When checking the wire harness, perform
steps (1) to (3). 
 
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 
1-11 
EAS20260 
SPECIAL TOOLS 
The following special tools are necessary for complete and accurate tune-up and assembly. Use only
the appropriate special tools as this will help prevent damage caused by the use of inappropriate tools
or improvised techniques. Special tools, part numbers or both may differ depending on the country.
When placing an order, refer to the list provided below to avoid any mistakes.
NOTE:
 
For U.S.A. and Canada, use part number starting with “YM-”, “YU-”, or “ACC-”. 
For others, use part number starting with “90890-”.  
Tool name/Tool No. IllustrationReference
pages  
Crankcase separating tool
90890-01135
Crankcase separator
YU-01135-B5-62
Ring nut wrench
90890-01268
Spanner wrench
YU-012684-51
Crankshaft installer pot
90890-01274
Installing pot
YU-900585-63
Crankshaft installer bolt
90890-01275
Bolt
YU-900605-63
Adapter (M12)
90890-01278
Adapter #3
YU-900635-63
YU-90058/YU-90059