Yamaha Wr 450 F Owners Manual

							6 - 18
–+ELECCHARGING SYSTEM
EC624000
COUPLERS AND LEADS CONNECTION 
INSPECTION
1. Check:
Couplers and leads connection
Rust/dust/looseness/short-circuit → 
Repair or replace.
CHARGING VOLTAGE INSPECTION
1. Start the engine.
2. Inspect:
Charging voltage
Out of specification → If no failure is
found in checking the source coil resis-
tance, replace the rectifier/regulator.
Tester (+) lead → Red lead 1 
Tester (–) lead → Black lead 2 
Charging 
voltageTester selector 
position
14.1 ~ 14.9 V at 
5,000 r/minDCV-20
R
BW Y1
2
3. Inspect:
Charging coil resistance
Out of specification → Replace.
Tester (+) lead → White lead 1 
Tester (–) lead → Ground 2 
Charging coil 
resistanceTester selector 
position
0.288 ~ 0.432 Ω 
at 20 ˚C (68 ˚F)Ω × 1 
						

							–+ELEC
6 - 19
TPS (THROTTLE POSITION SENSOR) SYSTEM
EC690000
TPS (THROTTLE POSITION SENSOR) SYSTEM
INSPECTION STEPS
If the TPS will not operate, use the following inspection steps.
NOTE:
Use the following special tools in this inspection.
Pocket tester:
YU-3112-C/90890-03112Inductive tachometer:
YU-8036-B
Engine tachometer:
90890-03113
Check entire ignition
system for connection.Repair or replace.
Check TPS. TPS coil Replace.
Check CDI unit.TPS input 
voltageReplace.
OK
OK
No good
No good
No good 
						

							6 - 20
–+ELECTPS (THROTTLE POSITION SENSOR) SYSTEM
HANDLING NOTE
CAUTION:
Do not loosen the screws {TPS (throttle
position sensor)} 1 except when changing
the TPS (throttle position sensor) due to
failure because it will cause a drop in
engine performance.
1
EC624000
COUPLERS AND LEADS CONNECTION 
INSPECTION
1. Check:
Couplers and leads connection
Rust/dust/looseness/short-circuit → 
Repair or replace.
TPS COIL INSPECTION
1. Inspect:
TPS coil resistance
Out of specification → Replace.
2. Loosen:
Throttle stop screw 1
NOTE:
Turn out the throttle stop screw until the throt-
tle shaft is in the full close position.Tester (+) lead → Blue lead 1 
Tester (–) lead → Black lead 2 
TPS coil
resistanceTester selector 
position
4 ~ 6 kΩ at
20 ˚C (68 ˚F)kΩ × 1 
						

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–+ELECTPS (THROTTLE POSITION SENSOR) SYSTEM
3. Inspect:
TPS coil variable resistance
Check that the resistance in increased
as the throttle grip is moved from the
full close position to the full open posi-
tion.
Out of specification → Replace.
Tester (+) lead → Yellow lead 1 
Tester (–) lead → Black lead 2 
TPS coil variable 
resistanceTester selec-
tor position
Full closed Full opened
kΩ × 1 0 ~ 2 kΩ at 
20 ˚C 
(68 ˚F)4 ~ 6 kΩ at 
20 ˚C 
(68 ˚F)
TPS REPLACEMENT AND ADJUSTMENT
1. Remove:
TPS coupler
Screw (TPS) 1 
TPS 2 
NOTE:
Loosen the screws (TPS) using the T25 bit.
2. Replace:
TPS
3. Install:
TPS 1 
Screw (TPS) 2 
TPS coupler
NOTE:
Align the slot a in the TPS with the projec-
tion b on the carburetor.
Temporarily tighten the screws (TPS).
12
21
b
a 
						

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–+ELECTPS (THROTTLE POSITION SENSOR) SYSTEM
4. Adjust:
Idle speed
Refer to “IDLE SPEED ADJUSTMENT”
section in the CHAPTER 3. 
5. Insert the thin electric conductors 2
(lead) into the TPS coupler 1, as shown,
and connect the tester to them.
CAUTION:
Do not insert the electric conductors
more than required because it may
reduce the waterproof function of the
coupler.
Make sure that a short-circuit does not
develop between the terminals because it
may cause damage to electrical compo-
nents.
6. Start the engine.Tester (+) lead → Yellow lead 3 
Tester (–) lead → Black lead 4 
7. Adjust:
TPS output voltage
Adjustment steps:
Adjust the installation angle of the TPS 1
to obtain the specified output voltage.
NOTE:
Measure the output voltage accurately with a
digital electronic voltmeter that gives an easy
reading of a small voltage.
TPS output 
voltageTester selector 
position
0.58 ~ 0.78 V DCV 
						

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–+ELECTPS (THROTTLE POSITION SENSOR) SYSTEM
8. Tighten:
Screw (TPS) 1 
9. Stop the engine.
1
EC694000
TPS INPUT VOLTAGE INSPECTION
1. Disconnect the TPS coupler.
2. Start the engine.
3. Inspect:
TPS input voltage
Out of specification → Replace the CDI
unit.
Tester (+) lead → Blue lead 1 
Tester (–) lead → Black/Blue lead 2 
TPS input 
voltageTester selector 
position
4 ~ 6 V DCV-20 
						

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6 - 24
LIGHTING SYSTEM
LIGHTING SYSTEM
INSPECTION STEPS
Refer to the following flow chart when inspecting the ignition system for possible problems.
NOTE:
Replace the bulb and/or bulb socket.
1) Seat
2) Fuel tank
Use the following special tool.
Check the bulb and bulb 
socket.Replace the bulb and/
or bulb socket.
Check the lights switch. Replace.
Check the AC magneto. Lighting coil Replace.
Check the entire lighting sys-
tem proper for connections.Repair or replace.
Check the rectifier/regulator.Out-put 
voltageReplace.
Pocket tester:
YU-3112-C/90890-03112Inductive tachometer:
YU-8036-B
Engine tachometer:
90890-03113
OK
OK
OK
OK
No good
No good
Improperly connected
No good
No good 
						

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–+ELECLIGHTING SYSTEM
LIGHTS SWITCH INSPECTION
1. Inspect:
Lights switch conduct
No continuous while being → Replace.
Continuous while being OFF → Replace. Tester (+) lead → Yellow lead 1 
Tester (–) lead → Blue lead 2 
Y
1L
2Tester selec-
tor position
Ω × 1
OFF
AC MAGNETO INSPECTION
1. Inspect:
Lighting coil resistance
Out of specification → Replace.
RECTIFIER/REGULATOR INSPECTION
1. Connect the battery leads.
2. Start the engine.
3. Turn on the headlight and taillight by turn-
ing on the lights switch.
4. Inspect:
Out-put voltage
Out of specification → Replace rectifier/
regulator. Tester (+) lead → Yellow lead 1 
Tester (–) lead → Ground 2 
Lighting coil
resistanceTester selector 
position
0.224 ~ 0.336 Ω 
at 20 ˚C (68 ˚F)Ω × 1
Tester (+) lead → Yellow lead 1 
Tester (–) lead → Black lead 2 
Out-put voltageTester selector 
position
13.0 ~ 14.0 V at 
5,000 r/minACV-20
R
BW
Y1
2 
						

							 
7 - 1
TUN
 
EC700000 
TUNING 
EC710000 
ENGINE 
Carburetor setting 
 
The air/fuel mixture will vary depending on
atmospheric conditions. Therefore, it is nec-
essary to take into consideration the air pres-
sure, ambient temperature, humidity, etc.,
when adjusting the carburetor. 
 
Perform a test run to check for proper engine
performance (e.g., throttle response) and
spark plug(-s) discoloration or fouling. Use
these readings to determine the best possi-
ble carburetor setting.
NOTE:
 
It is recommended to keep a record of all car-
buretor settings and external conditions (e.g.,
atmospheric conditions, track/surface condi-
tions, lap times) to make future carburetor set- 
ting easier.
WARNING
 
 
The carburetor is a part of the fuel line.
Therefore, be sure to install it in a well-
ventilated area, away from flammable
objects and any sources of fire. 
 
Never look into the carburetor intake.
Flames may shoot out from the pipe if the
engine backfires while it is being started.
Gasoline may be discharged from the
accelerator pump nozzle when the carbu- 
retor has been removed. 
SETTING 
 
7  
						

							 
7 - 2
TUN
CAUTION:
 
 
The carburetor is extremely sensitive to
foreign matter (dirt, sand, water, etc.).
During installation, do not allow foreign
matter to get into the carburetor. 
 
Always handle the carburetor and its
components carefully. Even slight
scratches, bends or damage to carbure-
tor parts may prevent the carburetor from
functioning correctly. Carefully perform
all servicing with the appropriate tools
and without applying excessive force. 
 
When the engine is stopped or when
riding at no load, do not open and close
the throttle unnecessarily. Otherwise, too
much fuel may be discharged, starting
may become difficult or the engine may
not run well. 
 
After installing the carburetor, check that
the throttle operates correctly and opens 
and closes smoothly.
Atmospheric conditions and carburetor
settings  
The air density (i.e., concentration of oxygen
in the air) determines the richness or lean-
ness of the air/fuel mixture. Therefore, refer
to the above table for mixture settings.
That is: 
 
Higher temperature expands the air with its
resultant reduced density. 
 
Higher humidity reduces the amount of oxy-
gen in the air by so much of the water vapor
in the same air. 
 
Lower atmospheric pressure (at a high alti-
tude) reduces the density of the air. 
Air temp. HumidityAir
pressure 
(altitude)Mixture Setting
High High Low (high) Richer Leaner
Low Low High (low) Leaner Richer 
SETTING