2016 YAMAHA WR 450F engine

ELECTRICAL COMPONENTS
9-61
1. Rectifier/regulator
2. Clutch switch
3. Ignition coil
4. ECU (engine control unit)
5. Fuel sender
6. Fuel pump
7. Battery
8. Resistor
9. Neutral switch
10.Radiator fan motor
11.Injector

ELECTRICAL COMPONENTS
9-65
1. Engine stop switch
2. Neutral switch
3. Clutch switch
4. Start switch

ELECTRICAL COMPONENTS
9-70
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5. Charge:• Battery
(refer to the appropriate charging method)
EWA
WARNING
Do not quick charge a battery.
ECA
NOTICE
• Do not use a high-rate battery charger since it forces a high-amperage current
into the battery quickly and can cause bat-
tery overheating and battery plate dam-
age.
• If it is impossible to regulate the charging current on the battery charger, be careful
not to overcharge the battery. • When charging a battery, be sure to re-
move it from the vehicle. (If charging has
to be done with the battery mounted on the
vehicle, disconnect the negative battery
lead from the battery terminal.)
• To reduce the chance of sparks, do not
plug in the battery charger until the battery
charger leads are connected to the bat-
tery.
• Before removing the battery charger lead clips from the battery terminals, be sure to
turn off the battery charger.
• Make sure the battery charger lead clips are in full contact with the battery terminal
and that they are not shorted. A corroded
battery charger lead clip may generate
heat in the contact area and a weak clip
spring may cause sparks.
• If the battery becomes hot to the touch at
any time during the charging process, dis-
connect the battery charger and let the
battery cool before reconnecting it. Hot
batteries can explode!
• As shown in the following illustration, the open-circuit voltage of a VRLA (Valve Reg-
ulated Lead Acid) battery stabilizes about
30 minutes after charging has been com-
pleted. Therefore, wait 30 minutes after
charging is completed before measuring
the open-circuit voltage.
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Charging method using a variable-cur-
rent (voltage) charger
a. Measure the open-circuit voltage prior to charging.
TIP
Voltage should be measur ed 30 minutes after
the engine is stopped.
Example
Open-circuit voltage = 12.0 V
Charging time = 6.5 hours
Charge of the battery = 20–30%
A. Open-circuit voltage (V)
B. Charging time (hours)
C. Relationship between the open-circuit voltage
and the charging time at 20°C (68°F)
D. These values vary wit h the temperature, the
condition of the battery plates, and the electro-
lyte level.
A. Open-circuit voltage (V)
B. Charging condition of the battery (%)
C. Ambient temperature 20°C (68°F)
A. Open-circuit voltage (V)
B. Time (minutes)
C. Charging
D. Ambient temperature 20°C (68°F)
E. Check the open-circuit voltage.

ELECTRICAL COMPONENTS
9-71
b. Connect a charger and ammeter to the bat-tery and start charging.
TIP
Set the charging voltage to 16–17 V. If the set-
ting is lower, charging will be insufficient. If too
high, the battery will be over-charged.
c. Make sure that the current is higher than the standard charging current written on the bat-
tery.
TIP
If the current is lower than the standard charg-
ing current written on the battery, set the charg-
ing voltage adjust dial at 20–24 V and monitor
the amperage for 3–5 minutes to check the bat-
tery.
d. Adjust the voltage so that the current is at
the standard charging level.
e. Set the time according to the charging time suitable for the open-circuit voltage.
f. If charging requires more than 5 hours, it is advisable to check the charging current after
a lapse of 5 hours. If there is any change in
the amperage, readjust the voltage to obtain
the standard charging current.
g. Measure the battery open-circuit voltage af-
ter leaving the battery unused for more than
30 minutes.
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Charging method using a constant volt-
age charger
a. Measure the open-circuit voltage prior to charging.
TIP
Voltage should be measured 30 minutes after
the engine is stopped.
b. Connect a charger and ammeter to the bat-tery and start charging.
c. Make sure that the current is higher than the
standard charging current written on the bat-
tery.
TIP
If the current is lower than the standard charg-
ing current written on the battery, this type of
battery charger cannot charge the VRLA (Valve
Regulated Lead Acid) battery. A variable volt-
age charger is recommended.
d. Charge the battery until the battery’s charg-ing voltage is 15 V.
TIP
Set the charging time at 20 hours (maximum).
e. Measure the battery open-circuit voltage af-ter leaving the battery unused for more than
30 minutes.
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6. Install:
• Battery terminals
7. Connect:
• Battery leads(to the battery terminals)
ECA
NOTICE
First, connect the positive battery lead “1”,
and then the negative battery lead “2”.
8. Check:• Battery terminalsDirt  Clean with a wire brush.
Loose connection  Connect properly.
9. Lubricate: • Battery terminals
10.Install: • Seat
• Side cover (left/right)
Refer to “GENERAL CHASSIS” on page 5-
1.
• Standard charging current is reached
Battery is good.
• Standard charging current is not reached Replace the battery.
12.8 V or more --- Charging is complete.
12.7 V or less --- Recharging is required.
Under 12.0 V --- Replace the battery.
12.8 V or more --- Charging is complete.
12.7 V or less --- Recharging is required.
Under 12.0 V --- Replace the battery.
Recommended lubricantDielectric grease
2
1

ELECTRICAL COMPONENTS
9-73
EAS2GC1388CHECKING THE DIODE
1. Check:•DiodeOut of specification  Replace.
TIP
The pocket tester and the analog pocket tester
readings are shown in the following table.
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a. Disconnect the diode from the wire harness.
b. Connect the pocket tester (  1) to the di-
ode coupler as shown.
c. Check the diode for continuity.
d. Check the diode for no continuity.
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EAS2GC1389CHECKING THE IGNITION SPARK GAP
1. Check: • Ignition spark gapOut of specification  Perform the ignition
system troubleshooting, starting with step 4.
Refer to “TROUBLESHOOTING” on page 9-
4.
TIP
If the ignition spark gap is within specification,
the ignition system circui t is operating normally.
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a. Remove the spark plug cap from the spark
plug.
b. Connect the ignition checker “1” as shown.
c. Push the engine stop switch.
d. Measure the ignition spark gap “a”.
e. Crank the engine by pushing the start switch and gradually increase the spark gap until a
misfire occurs.
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EAS2GC1390CHECKING THE SPARK PLUG CAP
1. Remove:• Spark plug cap
(from the spark plug lead)
2. Check: • Spark plug cap resistance
Out of specification  Replace.
Result
Continuity
(between “3” to “4”)
Pocket tester 90890-03112
Analog pocket tester YU-03112-C
No continuity Tester positive lead  Sky blue
“1”
Tester negative lead  Green/
Black “2”
Continuity Tester positive lead  Green/
Black “2”
Tester negative lead  Sky blue
“1”
No continuity Tester positive lead  Red “3”
Tester negative lead  Red/Blue
“4”
Continuity Tester positive lead  Red/Blue
“4”
Tester negative lead  Red “3”
2
1
4
3
R
Sb
G/B R/L
Minimum ignition spark gap 6.0 mm (0.24 in)
Ignition checker 90890-06754
Oppama pet–4000 spark checker YM-34487
2. Spark plug cap
Resistance 7.50–12.50 k 

ELECTRICAL COMPONENTS
9-76
b. Check the starter motor operation.
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EAS28150CHECKING THE STATOR COIL
1. Disconnect:• Stator coil coupler(from the wire harness)
2. Check:
• Stator coil resistanceOut of specification  Replace the stator
coil.
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a. Connect the pocket tester (  1) to the sta-
tor coil coupler as shown. b. Measure the stator coil resistance.
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EAS2GC1395CHECKING THE RECTIFIER/REGULATOR
1. Check:
• Charging voltageOut of specification  Replace the rectifier/
regulator.
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a. Set the digital tachometer to the ignition coil.
b. Connect the pocket tester (DC 20 V) to the rectifier/regulator coupler as shown.
c. Start the engine and let it run at approxi- mately 5000 r/min.
d. Measure the charging voltage.
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Stator coil resistance 0.528–0.792  (W–W)
Pocket tester 90890-03112
Analog pocket tester YU-03112-C
• Positive tester probe 
White “1”
• Negative tester probe 
White “2”
• Positive tester probe  White “1”
• Negative tester probe 
White “3”
• Positive tester probe  White “2”
• Negative tester probe 
White “3”
No load regulated voltage 14.1–14.9 V
Digital tachometer 90890-06760
Digital tachometer YU-39951-B
Pocket tester 90890-03112
Analog pocket tester YU-03112-C
• Positive tester probe  Red “1”
• Negative tester probe 
Black “2”
123
12

ELECTRICAL COMPONENTS
9-80
c. Start the engine.
d. Measure the throttle position sensor input voltage.
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EAS2GC1403CHECKING THE INTAKE AIR PRESSURE
SENSOR
1. Check:
• Intake air pressure sensor output voltageOut of specification  Replace.
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a. Connect the pocket tester (20 VDC) to the
intake air pressure sensor coupler (wire har-
ness side). b. Start the engine.
c. Measure the intake air pressure sensor out-
put voltage.
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EAS2GC1404CHECKING THE INTAKE AIR TEMPERA-
TURE SENSOR
1. Remove:• Intake air temperature sensor(from the air filter case)
EWA
WARNING
• Handle the intake air temperature sensor with special care.
• Never subject the intake air temperature sensor to strong shocks. If the intake air
temperature sensor is dropped, replace it.
2. Check: • Intake air temperature sensor resistanceOut of specification  Replace.
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a. Connect the pocket tester (  1k/100) to
the intake air temperature sensor terminal.
• Positive tester probe 
Blue “1”
• Negative tester probe 
Black/Blue “2”
Intake air pressure sensor output
voltage3.61–3.67 V at 101.3 kPa (3.61–
3.67 V at 1.01kgf/cm
2, 3.61–3.67
V at 14.7 psi)
Pocket tester 90890-03112
Analog pocket tester YU-03112-C
• Positive tester probe 
Pink “1”
• Negative tester probe 
Black/Blue “2”
21
Intake air temperature sensor re-
sistance 290–390  at 80 °C (290–390 
at 176 °F)
Pocket tester 90890-03112
Analog pocket tester YU-03112-C
• Positive tester probe  Brown/White “1”
• Negative tester probe 
Black/Blue “2”
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10
TROUBLESHOOTING
TROUBLESHOOTING.................................................................................... 10-1
GENERAL INFORMATION ...................................................................... 10-1
STARTING FAILURES ............................................................................. 10-1
INCORRECT ENGINE IDLING SPEED ................................................... 10-1
POOR MEDIUM-AND-HIGH-SPEED PERFORMANCE .......................... 10-2
SHIFTING IS DIFFICULT ......................................................................... 10-2
SHIFT PEDAL DOES NOT MOVE ........................................................... 10-2
JUMPS OUT OF GEAR............................................................................ 10-2
CLUTCH SLIPS ........................................................................................ 10-2
CLUTCH DRAGS ..................................................................................... 10-2
OVERHEATING ....................................................................................... 10-2
OVERCOOLING ....................................................................................... 10-3
POOR BRAKING PERFORMANCE ......................................................... 10-3
FRONT FORK OIL LEAKING ................................................................... 10-3
FAULTY FRONT FORK LEGS ................................................................. 10-3
UNSTABLE HANDLING ........................................................................... 10-3
HEADLIGHT DOES NOT COME ON ....................................................... 10-4
HEADLIGHT BULB BURNT OUT............................................................. 10-4
TAILLIGHT DOES NOT COME ON ......................................................... 10-4
LIST OF SELF-DIAGNOSTIC AND FAIL-SAFE ACTIONS ........................... 10-5