2015 YAMAHA WR 250F ignition

ENGINE
3-18
8. Install:
• Oil filler cap
9. Check:
• Oil level
Refer to “CHECKING THE ENGINE OIL
LEVEL” on page 3-16.
10.Check:
• Engine oil pressure
▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼
a. Slightly loosen the oil pressure check bolt
“1”.
EWA
WARNING
When the engine is started with the check
bolt removed, oil will spout; therefore, al-
ways loosen it before the checkup.
Start the engine and keep it idling until oil
starts to seep from the oil pressure check
bolt.
EWA
WARNING
Always keep the engine idling speed during
the checkup without increasing the engine
speed.
ECA
NOTICE
If no engine oil seeps out after one minute,
immediately turn the engine off so it will not
seize.
b. If no engine oil seeps out, check the engine
oil for leaks, and the engine oil passage and
the oil pump for damage.
c. Check the oil pressure again.
d. Tighten the oil pressure check bolt.
▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲
EAS2GB2100
ADJUSTING THE ENGINE IDLING SPEED
TIP
• Because the air pressure is lower at high alti-
tudes, the air-fuel mixture will become richer.
If the idling speed is low, turn the starter knob/
idle screw a few clicks counterclockwise to in-
crease the speed before the adjustment.
• Before adjusting the engine idling speed,
make sure that the air filter element is not
clogged, the engine compression is proper,
and the throttle grip free play is proper.
• Adjust the engine idling speed with the starter
knob/idle screw pushed in completely.
1. Start the engine, and warm this up until the
oil has reached the specified temperature.
2. Attach the pocket tester with temperature
probe “1” to the oil drain bolt.
3. Install:
• Digital tachometer
TIP
Get the high tension cord “1” of the ignition coil
pinched in the detector “a” of the digital tachom-
eter.
Oil pressure check bolt
10 Nm (1.0 m·kgf, 7.2 ft·lbf)
1
T R..
Oil temperature
70.0–80.0 °C (158.00–176.00 °F)
Digital tachometer
90890-06760
Digital tachometer
YU-39951-B
1
1 1
a a

ELECTRICAL SYSTEM
3-39
EAS2GB2132
ELECTRICAL SYSTEM
EAS2GB2133CHECKING THE SPARK PLUG
1. Remove:
• Seat
• Air scoop (left/right)
Refer to “GENERAL CHASSIS” on page 5-
1.
• Fuel tank “1”
Refer to “FUEL TANK” on page 8-1.
ECA
NOTICE
Do not use too much force to pull the hose.
TIP
Remove the fuel tank, turn this 180 ° clockwise,
and put it in the frame “2” as shown.
2. Remove:
• Spark plug cap
• Spark plug
Refer to “CAMSHAFT” on page 6-11.
ECA
NOTICE
In order not to allow the dirt accumulated
around the spark plug to drop from the
spark plug hole into the cylinder, clean it be-
fore removing the spark plug.
3. Check:
• Spark plug type
Wrong type  Replace.
4. Check:
• Electrode
Damage/wear  Replace the spark plug.
• Insulator
Abnormal color  Replace the spark plug.
Normal color is medium-to-light tan.5. Clean:
• Spark plug
(with a spark plug cleaner or a wire brush)
6. Measure:
• Spark plug gap “a”
Out of specification  Adjust the spark plug
gap.
7. Install:
• Spark plug
TIP
Before installing the spark plug, clean the spark
plug and gasket surface.
8. Install:
• Spark plug cap
• Fuel tank
• Air scoop (left/right)
• Seat
• Side cover (left/right)
Refer to “GENERAL CHASSIS” on page 5-
1.
EAS2GB2134CHECKING THE IGNITION TIMING
1. Remove:
• Timing mark accessing screw “1”
Manufacturer/model
NGK/LMAR8G
1
1
2
Spark plug gap
0.7–0.8 mm (0.028–0.031 in)
Spark plug
13 Nm (1.3 m·kgf, 9.4 ft·lbf)
T R..
1

ELECTRICAL SYSTEM
3-40
2. Attach:
• Timing light “1”
• Digital tachometer “2”
To the high tension code “3”.
3. Adjust:
• Engine idling speed
Refer to “ADJUSTING THE ENGINE
IDLING SPEED” on page 3-18.
4. Check:
• Ignition timing
Check whether the alignment mark “a” on
the left crankcase cover is within the firing
range “b” on the rotor.
Incorrect firing range  Check rotor and
Crankshaft position sensor.
5. Install:
• Timing mark accessing screw
EAS2GB2135
CHECKING AND CHARGING THE BATTERY
Refer to “CHECKING AND CHARGING THE
BATTERY” on page 9-69.
EAS2GB2136REPLACING THE HEADLIGHT BULBEWA
WARNING
Since the headlight bulb gets extremely hot,
keep flammable products and your hands
away from the bulb until it has cooled down.
1. Remove:
• Headlight unit bolt “1”
TIP
After you have removed the headlight unit
bolts, lift and remove the headlight unit.
2. Remove:
• Headlight coupler “1”
• Bulb cover “2”
3. Remove:
• Headlight bulb “1” Timing light
90890-03141
Timing light
YU-03141
Digital tachometer
90890-06760
Digital tachometer
YU-39951-B
Timing mark accessing screw
6 Nm (0.6 m·kgf, 4.3 ft·lbf)
2
1
3
ba
T R..
11
1
2
1

ENGINE REMOVAL
6-3
Removing the electronic parts
Order Part name Q’ty Remarks
Use a suitable stand to raise the front wheel
off the ground.
Seat Refer to “GENERAL CHASSIS” on page 5-1.
Side cover (left/right) Refer to “GENERAL CHASSIS” on page 5-1.
Air scoop (left / right) Refer to “GENERAL CHASSIS” on page 5-1.
Fuel tank Refer to “FUEL TANK” on page 8-1.
Air filter case cover
1 Rectifier/regulator 1
2ECU 1
3 Ignition coil 1
4 Neutral switch 1
5 AC magneto coupler 1 Disconnect.
6 Crankshaft position sensor coupler 1 Disconnect.
7 Coolant temperature sensor coupler 1 Disconnect.
For installation, reverse the removal proce-
dure.
T.R.
T.R.
T.R.T.R.
7 3
6
5
142
LT
New
LS

THROTTLE BODY
8-7
EAS2GB2353
THROTTLE BODY
Removing the throttle body
Order Part name Q’ty Remarks
Seat Refer to “GENERAL CHASSIS” on page 5-1.
Side cover (left/right) Refer to “GENERAL CHASSIS” on page 5-1.
Air scoop (left/right) Refer to “GENERAL CHASSIS” on page 5-1.
Fuel tank Refer to “FUEL TANK” on page 8-1.
ECU Refer to “ENGINE REMOVAL” on page 6-1.
Ignition coil Refer to “ENGINE REMOVAL” on page 6-1.
1 Intake air temperature sensor coupler 1 Disconnect.
2 Breather hose 3 1
3 Air filter case 1
4 Fuel injector coupler 1 Disconnect.
5 Intake air pressure sensor coupler 1 Disconnect.
6 Throttle position sensor coupler 1 Disconnect.
7 Throttle cable cover 1
8 Throttle cable 2
3
1
2
7
11
12
10
9
4
8
6
5
3.5 Nm (0.35 m kgf, 2.5 ft Ibf)T.R.
3.5 Nm (0.35 m kgf, 2.5 ft Ibf)T.R.
7 Nm (0.7 m kgf, 5.1 ft Ibf)T.R.
3.0 Nm (0.30 m kgf, 2.2 ft Ibf)T.R.
10 Nm (1.0 m kgf, 7.2 ft Ibf)T.R.

9
ELECTRICAL SYSTEM
IGNITION SYSTEM.......................................................................................... 9-2
CIRCUIT DIAGRAM ................................................................................... 9-2
TROUBLESHOOTING ............................................................................... 9-4
ELECTRIC STARTING SYSTEM..................................................................... 9-6
CIRCUIT DIAGRAM ................................................................................... 9-6
STARTING CIRCUIT CUT-OFF SYSTEM OPERATION ........................... 9-8
TROUBLESHOOTING ............................................................................. 9-10
CHARGING SYSTEM..................................................................................... 9-12
CIRCUIT DIAGRAM ................................................................................. 9-12
TROUBLESHOOTING ............................................................................. 9-14
LIGHTING SYSTEM....................................................................................... 9-16
CIRCUIT DIAGRAM ................................................................................. 9-16
TROUBLESHOOTING ............................................................................. 9-18
SIGNALING SYSTEM.................................................................................... 9-20
CIRCUIT DIAGRAM ................................................................................. 9-20
TROUBLESHOOTING ............................................................................. 9-22
COOLING SYSTEM........................................................................................ 9-24
CIRCUIT DIAGRAM ................................................................................. 9-24
TROUBLESHOOTING ............................................................................. 9-26
FUEL INJECTION SYSTEM........................................................................... 9-28
CIRCUIT DIAGRAM ................................................................................. 9-28
ECU SELF-DIAGNOSTIC FUNCTION ..................................................... 9-30
TROUBLESHOOTING METHOD ............................................................. 9-31
YAMAHA DIAGNOSTIC TOOL ................................................................ 9-32
TROUBLESHOOTING DETAILS ............................................................. 9-35
FUEL PUMP SYSTEM.................................................................................... 9-56
CIRCUIT DIAGRAM ................................................................................. 9-56
TROUBLESHOOTING ............................................................................. 9-58

ELECTRICAL COMPONENTS....................................................................... 9-60
CHECKING THE SWITCHES .................................................................. 9-64
CHECKING THE BULBS AND BULB SOCKETS .................................... 9-67
CHECKING THE FUSES ......................................................................... 9-68
CHECKING AND CHARGING THE BATTERY ........................................ 9-69
CHECKING THE RELAYS ....................................................................... 9-72
CHECKING THE DIODE .......................................................................... 9-73
CHECKING THE IGNITION SPARK GAP................................................ 9-73
CHECKING THE SPARK PLUG CAP ...................................................... 9-73
CHECKING THE IGNITION COIL ............................................................ 9-74
CHECKING THE CRANKSHAFT POSITION SENSOR........................... 9-74
CHECKING THE LEAN ANGLE SENSOR............................................... 9-75
CHECKING THE STARTER MOTOR OPERATION ................................ 9-75
CHECKING THE STATOR COIL ............................................................. 9-76
CHECKING THE RECTIFIER/REGULATOR ........................................... 9-76
CHECKING THE SPEED SENSOR ......................................................... 9-77
CHECKING THE FUEL SENDER ............................................................ 9-77
CHECKING THE RESISTER ................................................................... 9-77
CHECKING THE RADIATOR FAN MOTOR ............................................ 9-78
CHECKING THE COOLANT TEMPERATURE SENSOR........................ 9-78
CHECKING THE THROTTLE POSITION SENSOR ................................ 9-79
CHECKING THE THROTTLE POSITION SENSOR INPUT VOLTAGE .. 9-79
CHECKING THE INTAKE AIR PRESSURE SENSOR ............................ 9-80
CHECKING THE INTAKE AIR TEMPERATURE SENSOR ..................... 9-80
CHECKING THE FUEL INJECTOR ......................................................... 9-81

IGNITION SYSTEM
9-2
EAS2GB2359
IGNITION SYSTEM
EAS2GB2360CIRCUIT DIAGRAM
ONOFF
ONOFF
B
AA
BBB
BBB
RRR
RRR/L
Br Br Br
Br Br
WWW(Gy)
(Gy)B/LGyWW WB Gy
B R
W W WWW W
BR
R,R/Y
G
R
Y/B
R,R/W
Br
RL/R
(B)R/YR/WBr/WL/G
Br/W,BrL/W
(B) (B)Br BrL/Y Y/R
G/YBrBBBrBrL/YY/W
(B)(B)BB GG/Y
RR/L
R Lg
W/B
(B) B
GyBrRW/BB/LLYPG/WB/Y
R/BLgG/YW
Br/W
OL/RY/BB/OL/BSbY/R L/Y P/L
Y/G
(Gy)R/L R/BR/LB/Y
R/WR/L
R/W,BrP/L
R/L R/L
(B)
(B)
(B)
(L)
(L)(B) BR/LLBR/L R/L R/L R/L R/L B/L B/L B/L B/L B/L B/L B/LL L L LBBBB
Br Br Br Br
B/LBr/W
B/LG/WLYB/L
B/LPLB/LY/GL
(B)
(B)B/OBB BSbW/B
Sb
SbG/B
L/G,L/WL/BBrG/BG/BB
BB
(B)
(B)L/BBB B
Br Br
Br BrBr
BB LY
(B)
(B)
(B)
(B)
(B)
GB
Ch Dg
Y B
BRW
Br R
B W
B/WR W
Ch DgYBBrR/WBW
BBBBBB
RRRRRR/L
BrBrBrBrBr
Br
Br
BrBrBrBrR/LR/LR/LR/LR/L
B
LLLP
PL
Y
Y
RR
Br
R/LR/L
R/L
P/L
P/L
R/L
R/L
R/L
R/B
R/B
L/RL/Y
L/Y
Y/R
Y/R
G/Y
G/YG/Y
G/Y
B/Y
B/Y
R/LB/LB/L
B/LB/LB/LY/G
Y/GB/L
B/OL/BY/BW/B
W/B
G/B
L/B
W/BW/B
L/BL/BL/GL/W
L/W
L/R
Br/W
Br/W
R/W
R/W
R/Y
R/Y
G/BG/B
G/B
B/O
B/LB/LB/LB/LB/LB/LB/L
G/W
G/W
Br/W
Br/W
R/WR/WBr
OOO
O
R
RGy
R
LLLLBBBB
B
B
B
B
BB
B
B
RRWW
Y
Y
Dg
Dg
Ch
Ch
RW
BrBrBrBr
Br
B
W
Sb
SbSb
SbBr
Br
B
Br
Lg
Lg
R/L
R
R
RR
Gy
B
WWWWWW
R
RRGGBB
B
Y/B
RB
BB
BBBBB
Br
Br
Br
B
B
L/G
B/L
B/WB/W