light YAMAHA WR 250F 2002 Service Manual

5 - 41
CHAS
EC5B0000
HANDLEBAR
Extent of removal:1 Handlebar removal
Extent of removal Order Part name Q’ty Remarks
Preparation for removalHANDLEBAR REMOVAL
Headlight
1 Decompression cable 1 Disconnect at the lever side.
2 Decompression lever holder 1
3 Clutch cable 1 Disconnect at the lever side.
4 Clutch lever holder 1
5 Engine stop switch 1
6 Light switch 1
7 Brake master cylinder 1 Refer to “REMOVAL POINTS”.
8 Throttle cable cap 1
9 Throttle cable #2 (pushed) 1 Disconnect at the throttle side.
10 Throttle cable #1 (pulled) 1 Disconnect at the throttle side.
11 Right grip 1 Refer to “REMOVAL POINTS”.
12 Tube guide 1
13 Grip cap cover 1
14 Collar 1
15 Left grip 1 Refer to “REMOVAL POINTS”.
16 Handlebar upper holder 2
17 Handlebar 1
1
HANDLEBAR

5 - 45
CHASHANDLEBAR
8. Install:
Brake master cylinder 1
Brake master cylinder bracket 2
Bolt (brake master cylinder bracket) 3
NOTE:
Install the bracket so that the arrow mark a
faces upward.
First tighten the bolt on the upper side of the
brake master cylinder bracket, and then
tighten the bolt on the lower side.
T R..9 Nm (0.9 m · kg, 6.5 ft · lb)
9. Install:
Light switch 1
T R..2 Nm (0.2 m · kg, 1.4 ft · lb)
10. Install:
Engine stop switch 1
Clutch lever holder 2
Bolt (clutch lever holder) 3
Decompression lever holder 4
Bolt (decompression lever holder) 5
Clamp 6
T R..4 Nm (0.4 m · kg, 2.9 ft · lb)
T R..4 Nm (0.4 m · kg, 2.9 ft · lb)
NOTE:
The engine stop switch, clutch lever holder,
decompression lever holder and clamp
should be installed according to the dimen-
sions shown.
Pass the engine stop switch lead in the mid-
dle of the clutch holder.

5 - 47
CHAS
EC560000
STEERING
Extent of removal:1 Lower bracket removal2 Bearing removal
Extent of removal Order Part name Q’ty Remarks
STEERING REMOVAL
WARNING
Support the machine securely so there is no
danger of it falling over.
Preparation for removal Hold the machine by placing the
suitable stand under the engine.
Headlight
Handlebar
Cable guide
Front fenderRefer to “HANDLEBAR” section.
1 Trip meter 1
2 Steering stem nut 1
3 Front fork 2 Refer to “FRONT FORK” section.
4 Upper bracket 1
5 Steering ring nut 1 Use special tool.
Refer to “REMOVAL POINTS”.
6 Lower bracket 1
7Ball race cover
1
2
1
STEERING

5 - 60
CHASREAR SHOCK ABSORBER
EC580000
REAR SHOCK ABSORBER
Extent of removal:1 Rear shock absorber removal2 Rear shock absorber disassembly
Extent of removal Order Part name Q’ty Remarks
Preparation for removalREAR SHOCK ABSORBER
REMOVAL
Hold the machine by placing the
suitable stand under the engine.
WARNING
Support the machine securely so there is nodanger of it falling over.
Seat and side covers Refer to “SEAT, FUEL TANK AND SIDE
COVERS” section in the CHAPTER 4.
Silencer Refer to “EXHAUST PIPE AND
SILENCER” section in the CHAPTER 4.
Drain the coolant. Refer to “COOLANT REPLACEMENT”
section in the CHAPTER 3.
Coolant reservoir Refer to “RADIATOR” section in the
CHAPTER 4.
1 Taillight connector 2
2 Band 2
3 Bolt (reservoir tank) 1
4 Clamp (air filter joint) 1 Only loosening.
5 Rear frame 1
6 Bolt (rear shock absorber-relay arm) 1Hold the swingarm.
7 Bolt (rear shock absorber-frame) 1
8 Rear shock absorber 1
12

5 - 67
CHASREAR SHOCK ABSORBER
8. Install:
Band 1
Taillight connector 2

6 - 1
–+ELEC

ELECTRICAL COMPONENTS AND WIRING DIAGRAM
EC600000
ELECTRICAL
EC610000
ELECTRICAL COMPONENTS AND WIRING DIAGRAM
EC611000
ELECTRICAL COMPONENTS
1
Headlight
2
Voltage regulator
3
Engine stop switch
4
Throttle position sensor
5
Taillight
6
Neutral switch
7
CDI magneto
8
Spark plug
9
Ignition coil
0
Light switch
A
CDI unit
COLOR CODE
B...................... Black
Br .................... Brown
G ..................... Green
Gy ................... Gray
L ...................... Blue
O ..................... Orange
P...................... Pink
R ..................... Red
Sb.................... Sky blue
EC612000
WIRING DIAGRAM
B/L
R/WL/W
LY
L
Y
B
1B L
YYLB
5LB
YBLB
LB
2
6
4 9
8
W
R Br
G PB/YP
B Br
G W
R
O
L Y B/LSbSb
B/L Y O
L
A
Y
Br
Gy
PGR
WB
L YL Y
B B/L
SbW
Sb
WL/W
R/WL/WSbR/WSb
W
O
B
0
7
BGyBGy
Y
BL
B
B
3B/WBB/WG/B
L
B YLB Y

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

–+ELEC
6 - 12
LIGHTING 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 light switch. Replace.
Check the CDI magneto. Lighting coil Replace.
Check the entire lighting sys-
tem proper for connections.Repair or replace.
Check the voltage regula-
tor.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

6 - 13
–+ELECLIGHTING SYSTEM
LIGHT SWITCH INSPECTION
1. Inspect:
Light switch continuity
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
CDI MAGNETO INSPECTION
1. Inspect:
Lighting coil resistance
Out of specification → Replace.
VOLTAGE REGULATOR INSPECTION
1. Start the engine.
2. Turn on the headlight and taillight by turn-
ing on the light switch.
3. Inspect:
Out-put voltage
Out of specification → Replace voltage
regulator. Tester (+) lead → Yellow lead 1
Tester (–) lead → Black lead 2
Lighting coil
resistanceTester selector
position
0.16 ~ 0.24 Ω at
20 ˚C (68 ˚F)Ω × 1
Tester (+) lead → Blue lead 1
Tester (–) lead → Black lead 2
Out-put voltageTester selector
position
13.3 ~ 14.3 V at
5,000 r/minACV-20
BL
1
2
1
2

7 - 2
TUN
CAUTION:


The carburetor is extremely sensitive to
foreign matter (dirt, sand, water, etc.).
During installation, do not allow foreign
matter to get into the carburetor.

Always handle the carburetor and its
components carefully. Even slight
scratches, bends or damage to carbure-
tor parts may prevent the carburetor from
functioning correctly. Carefully perform
all servicing with the appropriate tools
and without applying excessive force.

When the engine is stopped or when
riding at no load, do not open and close
the throttle unnecessarily. Otherwise, too
much fuel may be discharged, starting
may become difficult or the engine may
not run well.

After installing the carburetor, check that
the throttle operates correctly and opens
and closes smoothly.
Atmospheric conditions and carburetor
settings
The air density (i.e., concentration of oxygen
in the air) determines the richness or lean-
ness of the air/fuel mixture. Therefore, refer
to the above table for mixture settings.
That is:

Higher temperature expands the air with its
resultant reduced density.

Higher humidity reduces the amount of oxy-
gen in the air by so much of the water vapor
in the same air.

Lower atmospheric pressure (at a high alti-
tude) reduces the density of the air.
Air temp. HumidityAir
pressure
(altitude)Mixture Setting
High High Low (high) Richer Leaner
Low Low High (low) Leaner Richer
SETTING