ignition YAMAHA WR 426F 2002 User Guide

3 - 49
INSP
ADJ
IGNITION TIMING CHECK
IGNITION TIMING CHECK
1. Remove:
Timing plug 1
2. Attach:
Timing light
Inductive tachometer
To the spark plug lead.
3. Check:
Ignition timing
Timing light:
YM-33277-A/90890-03141
Inductive tachometer:
YU-8036-B
Engine tachometer:
90890-03113
Checking steps:
Start the engine and let it warm up. Let the
engine run at the specified speed.
Engine speed:
1,700 ~ 1,900 r/min
Visually check the stationary pointer a is
within the firing range b on the rotor.
Incorrect firing range → Check rotor and
pickup assembly.
4. Install:
Timing plug

6 - 1
–+ELECELECTRICAL COMPONENTS AND WIRING DIAGRAM
EC600000
ELECTRICAL
EC610000
ELECTRICAL COMPONENTS AND WIRING DIAGRAM
EC611000
ELECTRICAL COMPONENTS
1Headlight
2“ENGINE STOP” button
3Regulator
4TPS (throttle position sensor)
5Tail light
6CDI magneto
7Neutral switch
8Ignition coil
9Spark plug
0Lights switch
ACDI unitCOLOR CODE
B ................... Black
Br .................. Brown
G ................... Green
Gy ................. Gray
L .................... Blue
O ................... Orange
P ................... Pink
R ................... Red
Sb ................. Sky blue
EC612000
WIRING DIAGRAM
* Except for USA
B/L
R/WL/W
LY
L
Y
B
1B L
L
B YL
B YYYLB
5LB
YBLB
LB
3
7
4 8
9
W
R Br
G PB/YP
B Br
G W
R
O
L Y B/LL/WSb
B/L Y O
L
A
Y
Br
Gy
PGR
WB
L YL Y
B B/L
SbW
Sb
WL/W
R/WL/WL/WR/WSb
W
O
B
0
6
B GyBGy
O
L Y Sb
B/L*
B*
Sb*
Y
BL
B
B
B
B/WBB/W G/B
2
W................... White
Y.................... Yellow
B/L................. Black/Blue
B/W ............... Black/White
B/Y ................ Black/Yellow
G/B ................ Green/Black
L/W................ Blue/White
R/W ............... Red/White

6 - 2
–+ELECMAP-CONTROLLED CDI UNIT
MAP-CONTROLLED CDI UNIT
A map-controlled, CDI ignition system is used in the WR426F/WR400F.
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.
CDI unit
Throttle position sensor
Pickup coil CDI magneto rotorIgnition coil
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)
Revolutions
Ignition timing
Throttle opening

6 - 3
–+ELECIGNITION 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.
*: 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.
Spark gap test*Clean or replace
spark plug.
Check entire ignition
system for connection.Repair or replace.
Check “ENGINE STOP”
button.Replace.
Check ignition coil. Primary coil Replace.
Secondary coil Replace.
Check CDI magneto. Pick-up coil Replace.
Source coil Replace.
Check neutral switch. Repair or replace.
Replace CDI unit.
Dynamic spark tester:
YM-34487
Ignition checker:
90890-06754Pocket tester:
YU-3112-C/90890-03112
No Spark
OK
OK
OK
OK
Spark
No good
No good
No good
No good
No good
No good
No good
OK

6 - 4
–+ELEC

IGNITION SYSTEM
EC622001
SPARK GAP TEST
1. Disconnect the spark plug cap from spark
plug.
2. Connect the dynamic spark tester
1
(ignition checker
2
) as shown.

Spark plug cap
3


Spark plug
4

Å
For USA and CDN
ı
Except for USA and CDN
3. Kick the kick starter.
4. Check the ignition spark gap.
5. 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

EC624000
COUPLERS AND LEADS CONNECTION
INSPECTION
1. Check:

Couplers and leads connection
Rust/dust/looseness/short-circuit
→

Repair or replace.
EC625001
“ENGINE STOP” BUTTON INSPECTION
1. Inspect:

“ENGINE STOP” button conduct
No continuity while being pushed
→
Replace.
Continuity while being freed
→
Replace.
Tester (+) lead
→
Black/White lead
1

Tester (–) lead
→
Black lead
2

B/W
1
B
2
Tester selec-
tor position
PUSH IN
Ω

×
1
FREE

6 - 5
–+ELECIGNITION SYSTEM
EC626002
IGNITION COIL INSPECTION
1. Inspect:
Primary coil resistance
Out of specification → Replace.
Tester (+) lead → Orange lead 1
Tester (–) lead → Black lead 2
Primary coil
resistanceTester selector
position
0.20 ~ 0.30 Ω at
20 ˚C (68 ˚F)Ω × 1
2. Inspect:
Secondary coil resistance
Out of specification → Replace.
NOTE:
When inspecting the secondary coil resis-
tance, remove the spark plug cap.
EC627011
CDI MAGNETO INSPECTION
1. Inspect:
Pick-up coil resistance
Out of specification → Replace. Tester (+) lead → Spark plug lead 1
Tester (–) lead → Orange lead 2
Secondary coil
resistanceTester selector
position
9.5 ~ 14.3 kΩ at
20 ˚C (68 ˚F)kΩ × 1
Tester (+) lead → Red lead 1
Tester (–) lead → White lead 2
Pick-up coil
resistanceTester selector
position
248 ~ 372 Ω at
20 ˚C (68 ˚F)Ω × 100

6 - 6
–+ELECIGNITION SYSTEM
2. Inspect:
Source coil 1 resistance
Out of specification → Replace.
3. Inspect:
Source coil 2 resistance
Out of specification → Replace. Tester (+) lead → Brown lead 1
Tester (–) lead → Green lead 2
Source coil 1
resistanceTester selector
position
640 ~ 960 Ω at
20 ˚C (68 ˚F)Ω × 100
Tester (+) lead → Pink lead 1
Tester (–) lead → Green lead 2
Source coil 2
resistanceTester selector
position
464 ~ 696 Ω at
20 ˚C (68 ˚F)Ω × 10
NEUTRAL SWITCH INSPECTION
1. Inspect:
Neutral switch conduct
* Except for USA
No continuity while in neutral → Replace.
Continuity while in gear → Replace.
ÅFor USA
ıExcept for USA
EC628000
CDI UNIT INSPECTION
Check all electrical components. If no fault is
found, replace the CDI unit. Then check the
electrical components again.Tester (+) lead → Blue/White lead 1
*Sky blue lead 1
Tester (–) lead → Ground
L/W
*Sb 1GroundTester selec-
tor position
NEU-
TRAL
Ω × 1
IN GEAR
–+ Ω×1
R/W
W Sb L/W
1
Å
–+ Ω×1
R/W
W Sb L/W
1
ı

6 - 7
–+ELECTPS (THROTTLE POSITION SENSOR) SYSTEM
EC690000
TPS (THROTTLE POSITION SENSOR) SYSTEM
INSPECTION STEPS
If the TPS will not operate, use the following inspection steps.
*marked: Refer to “IGNITION SYSTEM” section.
NOTE:
Use the following special tools in this inspection.
Check entire ignition
system for connection.Repair or replace.
Check TPS. TPS coil Replace.
*Check CDI magneto. Source coil Replace.
Check CDI unit.TPS input
voltageReplace.
Pocket tester:
YU-3112-C/90890-03112Inductive tachometer:
YU-8036-B
Engine tachometer:
90890-03113
No good
No good
No good
No good
OK
OK
OK

6 - 12
–+ELECLIGHTING 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 CDI magneto. Lighting coil Replace.
Check the entire lighting sys-
tem proper for connections.Repair or replace.
Check the regulator.Out-put volt-
ageReplace.
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