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...

 
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...

 
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) 
...

 
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  
→...

 
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...

 
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-...

 
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 
...

 
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...