ignition YAMAHA YZ250F 2002 User Guide

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ELECTRICAL COMPONENTS AND WIRING DIAGRAM
EC600000
ELECTRICAL
EC610000
ELECTRICAL COMPONENTS AND WIRING DIAGRAM
EC611000
ELECTRICAL COMPONENTS
1
Engine stop switch
2
Throttle position sensor
3
Neutral switch
4
CDI magneto
5
Spark plug
6
Ignition coil
7
CDI unit
COLOR CODE
B...................... Black
Br .................... Brown
G ..................... Green
L ...................... Blue
O ..................... Orange
P...................... Pink
R ..................... Red
Sb.................... Sky blue
EC612000
WIRING DIAGRAM
7
16
5
2 3 4
LY
BYL
B/LL
G
P
W
R
Y
B
G
B/YR PBrWG
RB Br WP
R/W WL/W SbW R/W Sb L/WY
B/LL Sb B OY
LB/L B OSbSb
L/WR/W
WSb
B/L
B/WG/B
B/W
Br
BB
LB
B/WB
Y
O
G/B
B/WB
B/W

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

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MAP-CONTROLLED CDI UNIT
MAP-CONTROLLED CDI UNIT
A map-controlled, CDI ignition system is used in the YZ250F.
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
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 throttle position sensor 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

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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.
*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:
90890-06754
Pocket tester:
YU-3112-C/90890-03112
Spark gap test*Clean or replace
spark plug.
Check entire ignition
system for connection.Repair or replace.
Check engine stop switch. Replace.
Check ignition coil. Primary coil Replace.
Secondary coil Replace.
Check CDI magneto. Pickup coil Replace.
Charging coil Replace.
Check neutral switch. Repair or replace.
Replace CDI unit.
No spark
OK
OK
OK
OK
OK
Spark
No good
No good
No good
No good
No good
No good
No good

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IGNITION SYSTEM
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 kickstarter crank.
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.
ENGINE STOP SWITCH INSPECTION
1. Inspect:

Engine stop switch conduct
No continuous while being pushed
→
Replace.
Continuous 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

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IGNITION 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.
CDI MAGNETO INSPECTION
1. Inspect:
Pickup 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
Pickup coil
resistanceTester selector
position
248 ~ 372 Ω at
20 ˚C (68 ˚F)Ω × 100

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2. Inspect:
Charging coil 1 resistance
Out of specification → Replace.
3. Inspect:
Charging coil 2 resistance
Out of specification → Replace. Tester (+) lead → Brown lead 1
Tester (–) lead → Green lead 2
Charging coil 1
resistanceTester selector
position
720 ~ 1,080 Ω
at 20 ˚C (68 ˚F)Ω × 100
Tester (+) lead → Pink lead 1
Tester (–) lead → Black lead 2
Charging coil 2
resistanceTester selector
position
44 ~ 66 Ω at
20 ˚C (68 ˚F)Ω × 10
NEUTRAL SWITCH INSPECTION
1. Inspect:
Neutral switch conduct
No continuous while in neutral → Replace.
Continuous while in gear → Replace.
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 → Sky blue lead 1
Tester (–) lead → Ground 2
Sb
1Ground
2Tester selec-
tor position
NEUTRALΩ × 1IN GEAR

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THROTTLE POSITION SENSOR SYSTEM
THROTTLE POSITION SENSOR SYSTEM
INSPECTION STEPS
If the throttle position sensor will not operate, use the following inspection steps.
*marked: Refer to “IGNITION SYSTEM” section.
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 throttle position
sensor.Throttle posi-
tion sensor coilReplace.
*Check CDI magneto. Charging coil Replace.
Check CDI unit.Throttle posi-
tion sensor
input voltageReplace.
OK
OK
OK
No good
No good
No good
No good