2003 YAMAHA WR 450F head

5 - 50
CHAS
4. Install:
Plain washer 1
Ring nut 2
Tighten the ring nut using the ring nut
wrench 3.
Refer to “STEERING HEAD INSPEC-
TION AND ADJUSTMENT” section in
the CHAPTER 3.
T R..7 Nm (0.7 m · kg, 5.1 ft · lb)
5. Check the steering shaft by turning it lock
to lock. If there is any binding, remove
the steering shaft assembly and inspect
the steering bearings.
6. Install:
Plain washer 1
7. Install:
Front fork 1
Handle crown 2
Main switch 3
Coupler bracket 4
Hose guide bracket 5
NOTE:
Install the coupler bracket on the outside of
the hose guide bracket.
Temporarily tighten the pinch bolts (under
bracket).
Do not tighten the pinch bolts (handle crown)
yet.
8. Install:
Plain washer 1
Steering shaft nut 2
T R..145 Nm (14.5 m · kg, 105 ft · lb)
STEERING

6 - 1
–+ELEC

ELECTRICAL COMPONENTS AND WIRING DIAGRAM
EC600000
ELECTRICAL
EC610000
ELECTRICAL COMPONENTS AND WIRING DIAGRAM
EC611000
ELECTRICAL COMPONENTS
1
Headlight
2
“ENGINE STOP”
button
3
Clutch switch
4
Diode
5
Starter relay diode
6
TPS (throttle posi-
tion sensor)
7
Starter relay
8
Fuse
9
Starting circuit
cut-off relay
0
Taillight
A
Neutral switch
B
Starter motor
C
AC magneto
D
Rectifier/regulator
E
Ignition coil
F
Spark plug
G
Start switch
H
Lights switch
I
Main switch
J
CDI unit
K
Battery
COLOR CODE
B.......................Black
Br .....................Brown
Gy ....................Gray
L .......................Blue
O ......................Orange
R ......................Red
Sb.....................Sky blue
W......................White
Y.......................Yellow
B/L....................Black/Blue
EC612000
WIRING DIAGRAM
1 2345
678
90
A B
CDEFGH
I
J
K
WR
WR
R
BR/BBr
R
BR/BBr
RW
L/RL/BBB
SbL/W
WY
YW
L/YBBB
WY
RYW
R
LY
B
YLB/L
B
B
ON
OFF
10A
BB
OFF
ON
OFF
STARTSTART
R-BrL/W
BLY
YLB-LB
B
BrL/W
BrL/W
L/B-LB
YL
B
L-B
L/WSb
B/WBBB
W/RB/W
R/BGyBrL/W
ON
STOP
OB
LYSbB/L
W RBrB/W
L/BGyWR/B
B O
L/YSbL/R
R W
Y W
Y W
Y B
B
L
L L
L B
B
B
RRR/B
B Br B
B B B B
L/W
R
R
R R B
R
BrBr
L/W L/W
Br B
L/B
L/B
L/R

Br
R/B
L/B L/W
B/W
W W/RW
RO
L
Y
B/L
O

B
L
Y
B/LSbL/WB/W
B
L/R L/Y L/Y
B
SbSbL/W
BGy
SbBB/LYO
L
∗2
O B
L YL/W
B/L
∗1
C
HD
BI
5
9
G3 4
A 2J
EF
6 7
K8
1
0
∗
2
∗1
∗2: Except for USA
∗1: For USA

B/W .................. Black/White
L/B ................... Blue/Black
L/R ................... Blue/Red
L/Y ................... Blue/Yellow
L/W .................. Blue/White
R/B................... Red/Black

6 - 4
–+ELEC

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

Å
For USA and CDN
ı
Except for USA and CDN
4. Kick the kickstarter.
5. Check the ignition spark gap.
6. Start engine, and increase spark gap until
misfire occurs. (for USA and CDN only)
Minimum spark gap:
6.0 mm (0.24 in)
Å
ı

COUPLERS, LEADS AND IGNITION COIL
CONNECTION INSPECTION
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 cyl-
inder head cover.
EC625001
“ENGINE STOP” BUTTON INSPECTION
1. Inspect:
“ENGINE STOP” button conduct
No continuity while being pushed → Replace.
Continuity while being freed → Replace.
2. Inspect:
Rubber part a
Tears/damage → Replace. Tester (+) lead → Black lead 1
Tester (–) lead → Black lead 2
B
1B
2Tester selector
position
PUSH IN
Ω × 1
FREE
a

6 - 25
–+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