2014 YAMAHA YZ250F diagram

REAR BRAKE
4-29
ASSEMBLING THE REAR BRAKE MASTER
CYLINDER
EWA13520
WARNING
• Before installation, clean and lubricate the
internal parts. Use new brake fluid for
cleaning and lubricating.
• Never use solvents on internal brake com-
ponents.
1. Wash the brake master cylinder and the
brake master cylinder kit with brake fluid.
2. Install:
• Primary cylinder cup “1”
• Secondary cylinder cup “2”
Install to the brake master cylinder piston
“3”.
EWA13520
WARNING
Apply brake fluid to the cylinder cups and
install them as shown. Wrong orientation in
installation causes poor braking perfor-
mance.
3. Install:
• Spring “1”
Install to the brake master cylinder piston
“2”.
TIP
Install the spring with a smaller inside diameter
to the brake master cylinder piston.4. Install:
• Master cylinder kit “1”
• Push rod “2”
• Circlip “3”
• Dust boot “4”
TIP
• Before installation, apply brake fluid to the
brake master cylinder kit.
• Before installation, apply silicone grease to
the push rod end.
• Use circlip pliers to install the circlip.
EAS1SM1160INSTALLING THE REAR BRAKE MASTER
CYLINDER
1. Install:
• Copper washers
• Brake hose
• Union bolt
EWA13530
WARNING
Proper brake hose routing is essential to in-
sure safe vehicle operation. Refer to “CA-
BLE ROUTING DIAGRAM” on page 2-31.
ECA1DX1008
NOTICE
Make sure that the pipe portion of the brake
hose touches the projection “a” on the
brake caliper. Recommended brake fluid
DOT 4
New
New
2
3
1
2
3
1Brake hose union bolt
30 Nm (3.0 m·kgf, 22 ft·lbf)
12
New
New
13
4
2NewNew
New
T R..

AC MAGNETO
5-60
2. Install:
• Woodruff key “1”
• Rotor “2”
TIP
• Clean the contact surfaces of the tapered por-
tions of the crankshaft and rotor.
• When installing the woodruff key, make sure
that its flat surface “a” is in parallel with the
crankshaft center line “b”.
• When installing the rotor, align the keyway “c”
of the rotor with the woodruff key.
3. Install:
• Washers
• Nut (rotor) “1”
4. Install:
• Dowel pin “1”
• Gasket (left crankcase cover) “2”
• Left crankcase cover “3”
• Lead holder “4”
• Bolt (left crankcase cover) “5”
TIP
Tighten the bolts in stages and in a crisscross
pattern.5. Connect:
• AC magneto lead
Refer to “CABLE ROUTING DIAGRAM” on
page 2-31.
Nut (rotor)
65 Nm (6.5 m·kgf, 47 ft·lbf)
Bolt (left crankcase cover)
10 Nm (1.0 m·kgf, 7.2 ft·lbf)
b11
c
2 a
T R..
1
New
T R..
1
1
2
3
5
5
5
5
4
45

8
ELECTRICAL SYSTEM
IGNITION SYSTEM.......................................................................................... 8-2
CIRCUIT DIAGRAM ................................................................................... 8-2
TROUBLESHOOTING ............................................................................... 8-4
CHARGING SYSTEM....................................................................................... 8-6
CIRCUIT DIAGRAM ................................................................................... 8-6
TROUBLE SHOOTING .............................................................................. 8-8
FUEL INJECTION SYSTEM........................................................................... 8-10
CIRCUIT DIAGRAM ................................................................................. 8-10
YAMAHA DIAGNOSTIC TOOL ................................................................ 8-12
TROUBLESHOOTING DETAILS ............................................................. 8-13
FUEL PUMP SYSTEM.................................................................................... 8-32
CIRCUIT DIAGRAM ................................................................................. 8-32
TROUBLESHOOTING ............................................................................. 8-34
ELECTRICAL COMPONENTS....................................................................... 8-36
.................................................................................................................. 8-36
CHECKING THE SWITCHES .................................................................. 8-38
CHECKING THE IGNITION SPARK GAP................................................ 8-41
CHECKING THE SPARK PLUG CAP ...................................................... 8-41
CHECKING THE IGNITION COIL ............................................................ 8-41
CHECKING THE CRANKSHAFT POSITION SENSOR........................... 8-42
CHECKING THE ECU .............................................................................. 8-43
CHECKING THE STATOR COIL ............................................................. 8-43
CHECKING THE RECTIFIER/REGULATOR ........................................... 8-43
CHECKING THE COOLANT TEMPERATURE SENSOR........................ 8-44
CHECKING THE THROTTLE POSITION SENSOR ................................ 8-44
CHECKING THE THROTTLE POSITION SENSOR
INPUT VOLTAGE .................................................................................... 8-45
CHECKING THE INTAKE AIR PRESSURE SENSOR ............................ 8-46
CHECKING THE INTAKE AIR TEMPERATURE SENSOR ..................... 8-46
CHECKING THE NEUTRAL SWITCH ..................................................... 8-46
CHECKING THE FUEL INJECTOR ......................................................... 8-47

IGNITION SYSTEM
8-2
EAS1SM1321
IGNITION SYSTEM
EAS1SM1322CIRCUIT DIAGRAM
B/LGy
BR
A
A
AA
B
RR R R R R R
B
B
B
RR
R
Lg
LgB/WB/Y
B/YB
B
BP
PP
Sb
B/LP/B
P/B
YL
YL
L
G/WBr/W
G/WBr/W
B/LB/L
B/L
B/L
B/R
B/R
R/B
R/B
O
OROR
OR
R
R
SbB
GyR
B/W
P L B/L
B/L Gy B/L B/L B/L B/L B/L
LL
PP
BBBB
PP
Sb
RB
B/RR
RB
B/Y PSb
BB
RR/B
LYB/L
B/W RLg
B/LBr/W
B/L P/B LB/LG/W
BB/Y
BB/L B/L B/L B/L B/L B/LBBBBRR
PPPL L LRR RR R
B
O P
Gy
R
B/Y Sb
P/B
R/B Lg B/RG/WBr/WB/L L Y
RB
B/L
Gy
R
O
O
R(BLACK) (BLACK)
B/W
4
1
3
2
5
67
8
10
9
1211
13
1415
16
17

IGNITION SYSTEM
8-5
8. Check the ignition system wire har-
ness.
Refer to “CIRCUIT DIAGRAM” on
page 8-2.NG 
Repair or replace the wire harness.
OK 
Replace the ECU.

CHARGING SYSTEM
8-6
EAS27200
CHARGING SYSTEM
EAS1SM1324CIRCUIT DIAGRAM
B/LGy
BR
A
A
AA
B
RR R R R R R
B
B
B
RR
R
Lg
LgB/WB/Y
B/YB
B
BP
PP
Sb
B/LP/B
P/B
YL
YL
L
G/WBr/W
G/WBr/W
B/LB/L
B/L
B/L
B/R
B/R
R/B
R/B
O
OROR
OR
R
R
SbB
GyR
B/W
P L B/L
B/L Gy B/L B/L B/L B/L B/L
LL
PP
BBBB
PP
Sb
RB
B/RR
RB
B/Y PSb
BB
RR/B
LYB/L
B/W RLg
B/LBr/W
B/L P/B LB/LG/W
BB/Y
BB/L B/L B/L B/L B/L B/LBBBBRR
PPPL L LRR RR R
B
O P
Gy
R
B/Y Sb
P/B
R/B Lg B/RG/WBr/WB/L L Y
RB
B/L
Gy
R
O
O
R(BLACK) (BLACK)
B/W
4
1
3
2
5
67
8
10
9
1211
13
1415
16
17

CHARGING SYSTEM
8-8
TROUBLE SHOOTING
The condenser is not being charged.
TIP
Before troubleshooting, remove the following part (s):
1. Seat
2. Air scoop (left)
1. Check the entire charging system’s
wiring.NG 
Reconnect.
OK 
2. Check the rectifier/regulator.
Refer to “CHECKING THE RECTI-
FIER/REGULATOR” on page 8-43.NG 
Replace the rectifier/regulator.
OK 
3. Check the stator coil.
Refer to “CHECKING THE STA-
TOR COIL” on page 8-43.NG 
Replace the stator coil.
OK 
4. Check the charging system wire
harness.
Refer to “CIRCUIT DIAGRAM” on
page 8-6.NG 
Repair or replace the wire harness.
OK 
Replace the condenser.

FUEL INJECTION SYSTEM
8-10
FUEL INJECTION SYSTEM
EAS1SM1327CIRCUIT DIAGRAM
B/LGy
BR
A
A
AA
B
RR R R R R R
B
B
B
RR
R
Lg
LgB/WB/Y
B/YB
B
BP
PP
Sb
B/LP/B
P/B
YL
YL
L
G/WBr/W
G/WBr/W
B/LB/L
B/L
B/L
B/R
B/R
R/B
R/B
O
OROR
OR
R
R
SbB
GyR
B/W
P L B/L
B/L Gy B/L B/L B/L B/L B/L
LL
PP
BBBB
PP
Sb
RB
B/RR
RB
B/Y PSb
BB
RR/B
LYB/L
B/W RLg
B/LBr/W
B/L P/B LB/LG/W
BB/Y
BB/L B/L B/L B/L B/L B/LBBBBRR
PPPL L LRR RR R
B
O P
Gy
R
B/Y Sb
P/B
R/B Lg B/RG/WBr/WB/L L Y
RB
B/L
Gy
R
O
O
R(BLACK) (BLACK)
B/W
4
1
3
2
5
67
8
10
9
1211
13
1415
16
17