2008 YAMAHA WR 450F Owners Manual

6-40
REAR SHOCK ABSORBER
7. Tighten:
• Screw (air filter joint) "1"
8. Install:
• Plastic band
• Taillight coupler
• Locking tieScrew (air filter joint):
3 Nm (0.3 m•kg, 2.2
ft•lb)

7-1
ELECTRICAL COMPONENTS AND WIRING DIAGRAM
ELECTRICAL
ELECTRICAL
COMPONENTS AND
WIRING DIAGRAM
ELECTRICAL COMPONENTS
1. Headlight
2. Multi-function display
3. Engine stop switch
4. Clutch switch
5. Diode
6. Starter relay diode
7. Throttle position sensor
8. Starter relay9. Fuse
10. Starting circuit cut-off relay
11. CDI unit
12. Taillight
13. Neutral switch
14. Starter motor
15. AC magneto
16. Rectifier/regulator17. Ignition coil
18. Spark plug
19. Start switch
20. Main switch
21. Speed sensor
22. Battery

7-2
ELECTRICAL COMPONENTS AND WIRING DIAGRAM
WIRING DIAGRAM
1. Headlight
2. Multi-function display
3. Engine stop switch
4. Clutch switch
5. Diode
6. Starter relay diode
7. Throttle position sensor
8. Starter relay
9. Fuse
10. Starting circuit cut-off relay
11. CDI unit
12. Taillight
13. Neutral switch
14. Starter motor
15. AC magneto
16. Rectifier/regulator
17. Ignition coil
18. Spark plug
19. Start switch
20. Main switch
21. Speed sensor
22. Battery
*1: For USA
*2: Except for USACOLOR CODE
BBlack
Br Brown
Ch Chocolate
Dg Dark green
GGreen
Gy Gray
LBlue
O Orange
RRed
Sb Sky blue
WWhite
YYellow
B/L Black/Blue
B/W Black/White
L/B Blue/Black
L/R Blue/Red
L/Y Blue/Yellow
L/W Blue/White
R/B Red/Black
R/W Red/White


7

7-3
IGNITION SYSTEM
IGNITION SYSTEM
INSPECTION STEPS
Use the following steps for checking the possibility of the malfunctioning engine being attributable to ignition system failure
and for checking the spark plug which will not spark.
*1 marked: Refer to "CHECKING THE FUSE" section in the CHAPTER 3.
*2 marked: Refer to "CHECKING AND CHARGING THE BATTERY" section in the CHAPTER 3.
*3 marked: Only when the ignition checker is used.
• Remove the following parts before inspection.
1. Seat
2. Fuel tank
• Use the following special tools in this inspection.
*1 Check fuse. No good→Replace fuse and check wire harness.
OK↓
*2 Check battery. No good→Recharge or replace.
OK↓
Spark gap test Spark→*3 Clean or replace spark plug.
No spark↓
Check entire ignition system for connection.
(couplers, leads and ignition coil)No good→
Repair or replace.
OK↓
Check engine stop switch. No good→Replace.
OK↓
Check main switch. No good→Replace.
OK↓
Check ignition coil. (primary coil and secondary
coil)No good→
Replace.
OK↓
Check AC magneto. (pickup coil) No good→Replace.
OK↓
Check neutral switch. No good→Repair or replace.
OK↓
Replace CDI unit.
Dynamic spark tester:
YM-34487
Ignition checker:
90890-06754
Pocket tester:
YU-3112-C/90890-03112

7-4
IGNITION SYSTEM
SPARK GAP TEST
1. Disconnect the ignition coil from
spark plug.
2. Remove the ignition coil cap.
3. Connect the dynamic spark tester
"1" (ignition checker "2") as
shown.
• Ignition coil "3"
• Spark plug "4"
A. For USA and CDN
B. Except for USA and CDN
4. Kick the kickstarter crank.
5. Check the ignition spark gap.
6. Start engine, and increase spark
gap until misfire occurs. (for USA
and CDN only)
CHECKING THE COUPLERS,
LEADS AND IGNITION COIL
CONNECTION
1. Check:
• Couplers and leads connection
Rust/dust/looseness/short-circuit
→Repair or replace.
• Ignition coil and spark plug as
they are fitted
Push in the ignition coil until it
closely contacts the spark plug
hole in the cylinder head cover.
CHECKING THE ENGINE STOP
SWITCH
1. Inspect:
• Engine stop switch conductionNot conductive while it is pushed→
Replace.
Conductive while it is freed→Re-
place.
Set the tester selection position to "Ω
× 1".
2. Inspect:
• Rubber part "a"
Tears/damage→ Replace.
CHECKING THE MAIN SWITCH
1. Inspect:
• Main switch conduction
Not conductive while the main switch
is moved to "ON"→Replace.
Conductive while the main switch is
moved to "OFF"→Replace.
Set the tester selection position to
"Ω×1".
2. Inspect:
• Main switch indicator light
Use 12 V battery.Indicator light does not come on→
Replace.
3. Inspect:
• Rubber part "a"
Tears/damage→Replace.
CHECKING THE IGNITION COIL
1. Remove the ignition coil cap.
2. Inspect:
• Primary coil resistance
Out of specification→Replace.
3. Inspect:
• Secondary coil resistance
Out of specification→Replace. Minimum spark gap:
6.0 mm (0.24 in)
Tester (+) lead→Black lead "1"
Tester (-) lead→Black lead "2"
Result
Conductive (while the
engine stop switch is
pushed)
Tester (+) lead→Red lead "1"
Tester (-) lead→Brown lead "2"
Result
Conductive (while the
main switch is moved
to "ON")Battery (+) lead→Red/Black lead
"1"
Battery (-) lead→Black lead "2"
Tester (+) lead→Orange lead "1"
Tester (-) lead→Black lead "2"
Primary
coil resis-
tanceTester se-
lector posi-
tion
0.08–0.10
Ω at 20 °C
(68 °F) Ω × 1
Tester (+) lead→Orange lead "1"
Tester (-) lead→Spark plug termi-
nal "2"
Secondary
coil resis-
tanceTester se-
lector posi-
tion
4.6–6.8
kΩat 20 °C
(68 °F) kΩ × 1

7-5
ELECTRIC STARTING SYSTEM
4. Inspect:
• Sealed portion of ignition coil "a"
• Spark plug terminal pin "b"
• Threaded portion of spark plug "c"
Wear →Replace.
CHECKING THE AC MAGNETO
1. Inspect:
• Pickup coil resistance
Out of specification→Replace.
CHECKING THE NEUTRAL
SWITCH
1. Inspect:
• Neutral switch conduction
Not conductive while it is in neutral→
Replace.
Conductive while it is engaged→Re-
place.
Set the tester selection position to "Ω
× 1".
CHECKING THE CDI UNIT
Check all electrical components. If no
fault is found, replace the CDI unit.
Then check the electrical compo-
nents again.
ELECTRIC STARTING
SYSTEM
STARTING CIRCUIT CUT-OFF
SYSTEM OPERATION
If the main switch is set to "ON", the
starter motor can only operate if at
least one of the following conditions is
met:
• The transmission is in neutral (the
neutral switch is closed).
• The clutch lever is pulled to the han-
dlebar (the clutch switch is closed).
The starting circuit cut-off relay pre-
vents the starter motor from operating
when neither of these conditions has
been met. In this instance, the start-
ing circuit cut-off relay is open so cur-
rent cannot reach the starter motor.
When at least one of the above con-
ditions has been met the starting cir-
cuit cut-off relay is closed and the
engine can be started by pressing the
start switch.
WHEN THE TRANSMISSION IS IN
NEUTRAL
WHEN THE CLUTCH LEVER IS
PULLED TO THE HANDLEBAR1. Battery
2. Main fuse
3. Main switch
4. Starting circuit cut-off relay
5. Start switch
6. Diode
7. Clutch switch
8. Neutral switch
9. Starter relay
10. Starter motor Tester (+) lead→Red lead "1"
Tester (-) lead→White lead "2"
Pickup coil
resistanceTester se-
lector posi-
tion
248–372 Ω
at 20 °C (68
°F) Ω × 100
Tester (+) lead→Sky blue lead "1"
Tester (-) lead→Ground "2"
Result
Conductive (while gear
is in neutral)

7-6
ELECTRIC STARTING SYSTEM
INSPECTION STEPS
If the starter motor will not operate, use the following inspection steps.
*1 marked: Refer to "CHECKING THE FUSE" section in the CHAPTER 3.
*2 marked: Refer to "CHECKING AND CHARGING THE BATTERY" section in the CHAPTER 3.
*3 marked: Refer to "CHECKING THE MAIN SWITCH" section.
*4 marked: Refer to "CHECKING THE NEUTRAL SWITCH" section.
• Remove the following parts before inspection.
1. Seat
2. Rear fender
• Use 12 V battery in this inspection.
• Use the following special tools in this inspection.
*1 Check fuse. No good→Replace fuse and check wire harness.
OK↓
*2 Check battery. No good→Recharge or replace.
OK↓
Check each coupler and wire connection. No good→Repair or replace.
OK↓
*3 Check main switch. No good→Replace.
OK↓
Check starter motor operation. No good→Repair or replace.
OK↓
Check starting circuit cut-off relay. No good→Replace.
OK↓
Check starter relay. No good→Replace.
OK↓
*4 Check neutral switch. No good→Replace.
OK↓
Check clutch switch. No good→Replace.
OK↓
Check diode. No good→Replace.
OK↓
Check start switch. No good→Replace.
Pocket tester:
YU-3112-C/90890-03112

7-7
ELECTRIC STARTING SYSTEM
CHECKING THE COUPLERS AND
LEADS CONNECTION
1. Check:
• Couplers and leads connection
Rust/dust/looseness/short-circuit
→Repair or replace.
CHECKING THE STARTER
MOTOR OPERATION
1. Connect the positive battery ter-
minal "1" and starter motor lead
"2" with a jumper lead "3".
Not operate→Repair or replace
the starter motor.
• A wire that is used as a jumper
lead must have at least the same
capacity or more as that of the
battery lead, otherwise the jump-
er lead may burn.
• This check is likely to produce
sparks, therefore make sure
nothing flammable is in the vicin-
ity.
CHECKING THE STARTING
CIRCUIT CUT-OFF RELAY
1. Remove:
• Starting circuit cut-off relay
2. Inspect:
• Starting circuit cut-off relay con-
duction
Use 12 V battery.
Not conductive while the battery is
connected→Replace.
Conductive while the battery is not
connected→Replace.
Set the tester selection position to "Ω
× 1".
CHECKING THE STARTER RELAY
1. Remove:
• Starter relay
2. Inspect:
• Starter relay conduction
Use 12 V battery.
Not conductive while the battery is
connected→Replace.
Conductive while the battery is not
connected →Replace.
Set the tester selection position to "Ω
× 1".
CHECKING THE CLUTCH SWITCH
1. Inspect:
• Clutch switch conduction
Not conductive while it is pulled→Re-
place.
Conductive while it is freed→Re-
place.
Set the tester selection position to "Ω
× 1".
CHECKING THE DIODE
1. Remove the diode from wire har-
ness.
2. Inspect:
• Diode continuity
Use pocket tester (tester selec-
tion position Ω × 1)
Incorrect continuity→Replace.
CHECKING THE START SWITCH
1. Inspect:
• Start switch conduction
Not conductive while it is pushed→
Replace.
Conductive while it is freed→Re-
place.
Set the tester selection position to "Ω
× 1".
Battery (+) lead→Blue/Black lead
"1"
Battery (-) lead→Brown lead "2"
Tester (+) lead→Blue/White lead
"3"
Tester (-) lead→Black lead "4"
Result
Conductive (while the
battery is connected)
Battery (+) lead→Starter relay ter-
minal "1"
Battery (-) lead→Starter relay ter-
minal "2"
Tester (+) lead→Starter relay ter-
minal "3"
Tester (-) lead→Starter relay ter-
minal "4"
Result
Conductive (while the
battery is connected)
Tester (+) lead→Black lead "1"
Tester (-) lead→Black lead "2"
Result
Conductive (while the
clutch lever is pulled)
Tester (+)→Blue/Red
terminal "1"
Tester (-) →Sky blue
terminal "2"Continu-
ous
Tester (+)→Blue/Red
terminal "1"
Tester (-)→Blue/Yel-
low terminal "3"Continu-
ous
Tester (+)→Sky blue
terminal "2"
Tester (-)→Blue/Red
terminal "1"No con-
tinuous
Tester (+)→Blue/Yel-
low terminal "3"
Tester (-)→Blue/Red
terminal "1"No con-
tinuous
Tester (+) lead→Black lead "1"
Tester (-) lead→Black lead "2"
Result
Conductive (while the
start switch is pushed)