2002 YAMAHA YZ250LC ad blue

2-11
MAINTENANCE SPECIFICATIONSSPEC
EC212300
ELECTRICAL
Part to be tightened Thread size Q’tyT ightening torqueNm m•kg ft•lb
Stator M 6 ×1.0 3 8 0.8 5.8
Rotor M10 ×1.25 1 41 4.1 30
Ignition coil M 6 ×1.0 2 7 0.7 5.1
Item Standard Limit
Ignition system:
Ignition timing (B.T.D.C.) 0.18 mm (0.007 in)…
Advancer type Electrical…
CDI:
Magneto-model (stator)/Manufacturer 5CU-01/YAMAHA…
Source coil 1 resistance (color) 720~1,080 Ωat 20°C (68°F)…
(Black-Black/Red)
Source coil 2 resistance (color) 44~66 Ωat 20°C (68°F)…
(Green/Blue-Green/White)
Pickup coil resistance (color) 248~372 Ωat 20°C (68°F)…
(White/Blue-White/Red)
CDI unit-model/Manufacturer 5NX-00/YAMAHA…
Ignition coil:
Model/Manufacturer 4MX-00/YAMAHA…
Minimum spark gap 6 mm (0.24 in)…
Primary winding resistance 0.20~0.30 Ωat 20°C (68°F)…
Secondary winding resistance 9.5~14.3 kΩat 20°C (68°F)…
5NX-9-30-2 6/7/01 1:57 PM Page 12

6-1
ELECTRICAL COMPONENTS AND WIRING DIAGRAMELEC
EC600000
ELECTRICAL
EC610000
ELECTRICAL COMPONENTS AND WIRING DIAGRAM
EC611000
ELECTRICAL COMPONENTS
1CDI unit
2“ENGINE STOP” button
3Ignition coil
4TPS (throttle position sensor)
5Solenoid valve
6CDI magneto
7Spark plug
EC612000
WIRING DIAGRAM
COLOR CODE
B...................Black
L ...................Blue
O ..................Orange
R ..................Red
Y...................Yellow
B/L................Black/Blue
B/R ...............Black/Red
B/W ..............Black/White
G/L ..............Green/Blue
G/W ..............Green/White
W/L...............White/Blue
W/R ..............White/Red
6
L
Y
B/LYL
B/LY LL
Y
B
B/W
B B/W
B
R
BB
RR
RR
R
B
B/R
G/L
G/W
W/R
W/L W/L B/R
G/L
W/R
B G/W G/L B/R W/L
G/W B W/R
O
B G/W G/L
Y B/L
L
W/R
W/L
B
R
B/R
B/W
O G/L
B/L
L
W/L
B
R
B/R
B/WG/W
Y
W/R
OB/L
5NX-9-30-6 6/5/01 4:44 PM Page 2

6-4
IGNITION SYSTEMELEC
EC626002
IGNITION COIL INSPECTION
1. Inspect:
9Primary coil resistance
Out of specification Replace.
2. Inspect:
9Secondary coil resistance
Out of specification Replace.
NOTE:
When inspecting the secondary coil resistance,
remove the spark plug cap.
EC627011
CDI MAGNETO INSPECTION
1. Inspect:
9Pick-up coil resistance
Out of specification Replace.
Tester (+) leadOrange lead 1
Tester (–) lead
Black lead 2
Tester (+) leadSpark plug lead 1
Tester (–) lead
Orange lead 2
Primary coil Tester selector
resistance position
0.20~0.30Ωat
Ω× 1
20°C (68°F)
Secondary coil Tester selector
resistance position
9.5~14.3kΩat
kΩ× 1
20°C (68°F)
Tester (+) leadWhite/Red lead 1
Tester (–) lead
White/Blue lead 2
Pick–up coil Tester selector
resistance position
248~372Ωat
Ω× 100
20°C (68°F)
5NX-9-30-6 6/5/01 4:44 PM Page 10

6-5
IGNITION SYSTEMELEC
2. Inspect:
9Source coil 1 resistance
Out of specification Replace.
3. Inspect:
9Source coil 2 resistance
Out of specification 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 (+) leadBlack/Red lead 1
Tester (–) lead
Blacklead 2
Source coil 1 Tester selector
resistance position
720~1,080Ωat
Ω× 100
20°C (68°F)
Tester (+) leadGreen/Blue lead 1
Tester (–) lead
Green/White lead 2
Source coil 2 Tester selector
resistance position
44~66Ωat
Ω× 10
20°C (68°F)
5NX-9-30-6 6/5/01 4:44 PM Page 12

6-9
TPS (THROTTLE POSITION SENSOR) SYSTEMELEC
L
Y
B1
21
2
EC624000
COUPLERS AND LEADS CONNECTION
INSPECTION
1. Check:
9Couplers and leads connection
Rust/ Dust/ Looseness/Short-circuit 
Repair or replace.
EC692000
TPS COIL INSPECTION
1. Remove:
9Carburetor
9Mixing chamber top
Refer to “CARBURETOR AND REED
VALVE” section in the CHAPTER 4.
2. Inspect:
9TPS coil resistance
Out of specification Replace.
Tester (+) leadBluelead 1
Tester (–) lead
Blacklead 2
TPS coil Tester selector
resistance position
4~6kΩat
kΩ×1
20°C (68°F)
EC69A000
HANDLING NOTE
cC
Do not loosen the screws {TPS (throttle
position sensor)} except when changing
the TPS (throttle position sensor) due to
failure because it will cause a drop in
engine performance.
5NX-9-30-6 6/5/01 4:44 PM Page 24

6-13
TPS (THROTTLE POSITION SENSOR) SYSTEMELEC
Y
LB/L
1
2 1
2
EC694000
TPS INPUT VOLTAGE INSPECTION
1. Disconnect the TPS coupler.
2. Start the engine.
3. Inspect:
9TPS input voltage
Out of specification Replace the CDI
unit.
Tester (+) leadBluelead 1
Tester (–) lead
Black/Bluelead 2
TPS input Tester selector
voltage position
4~6V DCV-20
5NX-9-30-6 6/5/01 4:44 PM Page 32

7-22
SETTINGTUN
EC72Q011
Rear shock absorber setting parts
9Rear shock spring 1
[Equal pitch spring ]
[Unequal pitch spring ]
NOTE:
9The unequal pitch spring is softer in initial char-
acteristic than the equal pitch spring and is diffi-
cult to bottom out under full compression.
9The I.D. color ais marked at the end of the
spring.
9Extent of adjustment (spring length)
SPRING SPRINGI.D.SPRING
TYPE
RATE PART NUMBERCOLORFREE
/POINTLENGTH
SOFT4.4 5DH-22212-70Brown/1260
4.6 5DH-22212-10Green/1260
STD 4.8 5DH-22212-20 Red/1 260
5.0 5DH-22212-30 Black/1 260
STIFF5.2 5DH-22212-40 Blue/1 260
5.4 5DH-22212-50
Yellow/1265
5.6 5DH-22212-60 Pink/1 265
SPRING
SPRINGI.D.SPRING
TYPE RATE
PART NUMBERCOLORFREE
(approx.)/POINTLENGTH
SOFT4.6 5ET-22212-20 Green/2 2754.8 5ET-22212-00 Red/2 275
*STD 5.0 5ET-22212-10 Black/2 275
STIFF5.2 5ET-22212-30 Blue
/2275
5.4 5ET-22212-40
Yellow/2 275
*For EUROPE
SPRING FREE EXTENT OF
LENGTH ADJUSTMENT b
260mm (10.24in)240.5~258.5mm(9.47~10.18in)
265mm (10.43in)245.5~263.5mm(9.67~10.37in)
275mm (10.83in)255.5~273.5mm(10.06~10.77in)
5NX-9-30-7 6/5/01 4:48 PM Page 48