Page 512 of 758
5 - 1
CHAS
EC500000
CHASSIS
EC590000
FRONT WHEEL AND REAR WHEEL
EC598000
FRONT WHEEL
FRONT WHEEL AND REAR WHEEL
Extent of removal:
1 Front wheel removal
2 Wheel bearing removal
3 Brake disc removal
Extent of removal Order Part name Q’ty Remarks
FRONT WHEEL REMOVAL
WARNING
Support the machine securely so there is nodanger of it falling over.
Preparation for removal Hold the machine by placing the
suitable stand under the engine.
1 Trip meter cable 1
2 Bolt (axle holder) 4 Only loosening.
3 Nut (front wheel axle) 1
4 Front wheel axle 1
5 Front wheel 1
6 Trip meter gear unit 1
7 Collar 1
8 Oil seal 1
9 Bearing 2 Refer to “REMOVAL POINTS”.
10 Brake disc 1
2
13
3
Page 514 of 758
5 - 2
CHAS
EC598100
REAR WHEEL
Extent of removal:
1 Rear wheel removal
2 Wheel bearing removal
3 Brake disc removal
Extent of removal Order Part name Q’ty Remarks
REAR WHEEL REMOVAL
WARNING
Support the machine securely so there is nodanger of it falling over.
Preparation for removal Hold the machine by placing the
suitable stand under the engine.
1 Nut (rear wheel axle) 1
2 Rear wheel axle 1
3 Chain puller 2
4 Rear wheel 1 Refer to “REMOVAL POINTS”.
5 Collar 2
6 Driven sprocket 1
7 Oil seal 2
8 Circlip 1
9 Bearing 2 Refer to “REMOVAL POINTS”.
10 Brake disc 1
3
3
1
2
FRONT WHEEL AND REAR WHEEL
Page 648 of 758

6 - 1
–+ELECELECTRICAL COMPONENTS AND WIRING DIAGRAM
EC600000
ELECTRICAL
EC610000
ELECTRICAL COMPONENTS AND WIRING DIAGRAM
EC611000
ELECTRICAL COMPONENTS
1Headlight
2“ENGINE STOP”
button
3Clutch switch
4Diode
5Starter relay diode
6TPS (throttle posi-
tion sensor)
7Starter relay
8Fuse
9Starting circuit
cut-off relay0Taillight
ANeutral switch
BStarter motor
CAC magneto
DRectifier/regulator
EIgnition coil
FSpark plug
GStart switch
HMain switch
ICDI unit
JBatteryCOLOR 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
C DEFG
H
I
J
WR
WR
WY
R
BR/BBr
R
BR/BBr
RW
YW
L/RL/BBB
SbL/W
L/YBBB
WY
RYW
R
LY
B
YLB/L
B
B
ON
OFF
10A
BB
OFF
STARTSTART
R-BrL/W
B
BrL/W
BrL/W
L/B
-YB
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
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/W∗1
Sb∗2B/W
B
L/R L/Y L/Y
B
SbSbL/W
BGy
SbBB/LYO
L
∗2
O B
L YL/W
B/L
∗1
CD
BH
5
9
G3 4
A 2I
EF
6 7
J8
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
Page 650 of 758

–+ELEC
6 - 2
MAP-CONTROLLED CDI UNIT
MAP-CONTROLLED CDI UNIT
A map-controlled, CDI ignition system is used in the WR450F.
The microcomputer in the CDI unit detects the engine speed and throttle position, thus determining
the optimum ignition timing through the entire operating range. In this way, quick throttle response
can be achieved according to various riding conditions.
Throttle position sensorCDI unitIgnition coil
Pickup coilAC magneto rotor
Function of Component
Component Function
TPS
(throttle position sensor)Detects throttle valve opening and inputs it into the computer in the
CDI unit as a throttle opening signal.
Pickup coil Detects signal rotor revolutions and inputs them into the computer in
the CDI unit as engine revolution signals.
CDI unit The signals of the TPS and pickup coil sensor are analyzed by the
computer in the CDI unit, which then adjusts ignition timing for the
operation requirements.
Principal of 3-Dimensional Control
Conventionally, ignition timing was controlled only
by engine revolutions (2-dimensional control).
However, ignition timing needs advancement also
by engine load. Thus, accurate ignition timing can
be determined by adding throttle opening to deter-
mine ignition timing (3-dimensional control).
3-D Image Map of Ignition Timing
(different from actual characteristics)
Ignition timing
Th
rot
t
le
o
peni
ngRev
o
lut
io
ns
Page 654 of 758

–+ELEC
6 - 3
IGNITION SYSTEM
EC620000
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 “FUSE INSPECTION” section in the CHAPTER 3.
*2 marked: Refer to “BATTERY INSPECTION AND CHARGING” section in the CHAPTER 3.
*3 marked: Only when the ignition checker is used.
NOTE:
Remove the following parts before inspection.
1) Seat
2) Fuel tank
Use the following special tools in this inspection.
Dynamic spark tester:
YM-34487
Ignition checker:
90890-06754Pocket tester:
YU-3112-C/90890-03112
*1 Check fuse.Replace fuse and
check wire harness.
*2 Check battery Recharge or replace.
Spark gap test*3 Clean or replace
spark plug.
Check entire ignition
system for connection.
(couplers, leads and
ignition coil)Repair or replace.
Check “ENGINE STOP”
button.Replace.
Check main switch. Replace.
Check ignition coil. Primary coil Replace.
Secondary coil Replace.
Check AC magneto. Pick-up coil Replace.
Check neutral switch. Repair or replace.
Replace CDI unit.
OK
OK
No spark
OK
OK
OK
OK
OK
OK
Spark No good
No good
No good
No good
No good No good
No good
No good
No good
Page 658 of 758

6 - 4
–+ELECIGNITION 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 (igni-
tion checker 2) as shown.
Ignition coil 3
Spark plug 4
ÈFor USA and CDN
ÉExcept 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)
È
É
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 fit-
ted
Push in the ignition coil until it closely
contacts the spark plug hole in the cylin-
der 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
1 B
2 Tester selec-
tor position
PUSH IN
Ω
×
×× × 1
FREE
a
Page 676 of 758
6 - 12
–+ELECELECTRIC STARTING SYSTEM
STARTER MOTOR
0
9
56
7
5 0 8
9
4
3
2
1
New
New
New
B
5
1
Extent of removal:
1 Starter motor disassembly
Extent of removal Order Part name Q’ty Remarks
STARTER MOTOR REMOVAL
Preparation for removal Drain the engine oil. Refer to “ENGINE OIL REPLACEMENT”
section in the CHAPTER 3.
Crankcase cover (left) Refer to “AC MAGNETO AND
STARTER CLUTCH” section in the
CHAPTER 4.
1 Starter motor 1
STARTER MOTOR DISASSEM-
BLY
1 Starter motor front cover 1
2 Washer (starter motor front
cover)1
3 Plain washer 1
4 Circlip 1
5 O-ring 3
1
Page 690 of 758
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