2006 YAMAHA YZ250F THROTTLE POSITION SENSOR

CHAPTER 6
ELECTRICAL
ELECTRICAL COMPONENTS
AND WIRING DIAGRAM............................6-1
MAP-CONTROLLED CDI UNIT..................6-2
IGNITION SYSTEM.....................................6-3
THROTTLE POSITION SENSOR
SYSTEM......................................................6-7
CHAPTER 7
TUNING
ENGINE.......................................................7-1
CHASSIS..................................................7-11

2 - 18
SPECCABLE ROUTING DIAGRAM
EC240000
CABLE ROUTING DIAGRAM
1Fuel tank breather hose
2Radiator hose 1
3Cylinder head breather hose
4Radiator hose 4
5Clutch cable
6Throttle position sensor lead
7Fuel hose
8Hot starter cable
9Carburetor breather hose
0Carburetor overflow hose
AConnector coverÈInsert the end of the fuel tank
breather hose into the hole in
the steering stem.
ÉPass the cylinder head
breather hose on the outside of
the radiator hose 1 and on the
inside of the radiator pipe (radi-
ator hose 4).
ÊPass the clutch cable through
the cable guides.
ËPass the clutch cable in front of
the radiator mounting boss.ÌPass the fuel hose between the
hot starter cable and throttle
position sensor lead.
ÍPass the carburetor breather
hoses and overflow hose so
that all there hoses do not con-
tact the rear shock absorber.
ÎInstall the connector cover so
that it does not come in
between the radiator hose 1
and radiator.
B A
99
0
Í
B
A
8
3A2Î
7
Ì
ËÉ
1
È
6
5
4
Ê

2 - 19
SPECCABLE ROUTING DIAGRAM
1Hot starter cable
2Radiator hose 2
3Clamp
4Ignition coil lead
5Throttle position sensor lead
6Hump (frame)
7Oil hose
8Hose guide
9Neutral switch lead
0CDI magneto lead
AClutch cable
BRadiator breather hose
CEngine stop switch leadDSub-wire harness
ECDI unit bracket
FCDI unit
GThrottle cable
HCylinder head breather hose
ÈFasten the hot starter cable,
throttle cables, throttle position
sensor lead and ignition coil
lead.
ÉFasten the throttle position
sensor lead behind the hump
of the frame.ÊFasten the neutral switch lead
on the oil hose.
ËPass the neutral switch lead on
the inside of the oil hose.
ÌFasten the neutral switch lead,
CDI magneto lead and radiator
breather hose.
ÍFasten the neutral switch lead,
CDI magneto lead, radiator
breather hose and clutch cable
over the radiator mounting
boss.
5Ð
Ð
B-B
C-C
E-E
H-H
G-G
D-D
A-A
G
4
5
1
7H
Ð B
B
0
9 F
3
Ñ
6 90F
È
9
CC
C E HH
GA
AB
E
7
3
8 3 9
Ê Ê
Ë
F
E
3
D
C
B
3
A
3
Ì Í Î Ï
1
2
3
4
5
6
3
B
0
9
A
0É
B
B 0 9
9
D
G
B
D
Ò 3

4 - 9
ENGCARBURETOR
CARBURETOR
3
97
8
4
4
2
T R..3 Nm (0.3 m • kg, 2.2 ft • Ib)
T R..3 Nm (0.3 m • kg, 2.2 ft • Ib)
T R..4 Nm (0.4 m •
kg, 2.9 ft • Ib)
T R..4 Nm (0.4 m •
kg, 2.9 ft • Ib)
T R..2 Nm (0.2 m •
kg, 1.4 ft • Ib)
T R..11 Nm (1.1 m •
kg, 8.0 ft • Ib)
5 1
6
6
Extent of removal:
1 Carburetor removal
Extent of removal Order Part name Q’ty Remarks
CARBURETOR REMOVAL
Preparation for removal Seat and fuel tank Refer to “SEAT, FUEL TANK AND SIDE
COVERS” section.
1Clamp 1
2 Throttle position sensor lead cou-
pler1
3 Throttle cable cover 1
4 Throttle cable 2
5 Clamp (air filter joint) 1 Loosen the screw (air filter joint).
6 Clamp (carburetor joint) 2 Loosen the screws (carburetor joint).
7 Hot starter plunger 1
8 Carburetor assembly 1
9 Carburetor joint 1
1

4 - 12
ENGCARBURETOR
HANDLING NOTE
CAUTION:
Do not loosen the screws (throttle position
sensor)
1 except when changing the throt-
tle position sensor due to failure because it
will cause a drop in engine performance.
1
REMOVAL POINTS
Pilot screw
1. Remove:
Pilot screw 1
NOTE:
To optimize the fuel flow at a small throttle
opening, each machine’s pilot screw has been
individually set at the factory. Before removing
the pilot screw, turn it in fully and count the
number of turns. Record this number as the
factory-set number of turns out.
INSPECTION
Carburetor
1. Inspect:
Carburetor body
Contamination → Clean.
NOTE:
Use a petroleum based solvent for cleaning.
Blow out all passages and jets with com-
pressed air.
Never use a wire.

4 - 21
ENG
3. Install:
Hot starter plunger 1
1T R..2 Nm (0.2 m · kg, 1.4 ft · lb)
4. Tighten:
Bolt (air filter joint) 1
Bolt (carburetor joint) 2
2
1
T R..3 Nm (0.3 m · kg, 2.2 ft · lb)
T R..3 Nm (0.3 m · kg, 2.2 ft · lb)
5. Install:
Throttle cable (pull) 1
Throttle cable (return) 2
6. Adjust:
Throttle grip free play
Refer to “THROTTLE CABLE ADJUST-
MENT” section in the CHAPTER 3.2
1
T R..4 Nm (0.4 m · kg, 2.9 ft · lb)
T R..11 Nm (1.1 m · kg, 8.0 ft · lb)
7. Install:
Throttle cable cover 1
Bolt (throttle cable cover) 2
2 1
T R..4 Nm (0.4 m · kg, 2.9 ft · lb)
8. Install:
Throttle position sensor lead coupler 1
Clamp 2
Refer to “CABLE ROUTING DIAGRAM”
section in the CHAPTER 2.
1
2
CARBURETOR

6 - 1
–+ELECELECTRICAL COMPONENTS AND WIRING DIAGRAM
EC600000
ELECTRICAL
EC610000
ELECTRICAL COMPONENTS AND WIRING DIAGRAM
EC611000
ELECTRICAL COMPONENTS
1Engine stop switch
2Throttle position sensor
3Neutral switch
4CDI magneto
5Ignition coil
6Spark plug
7CDI unitCOLOR CODE
B ...................... Black
Br .................... Brown
G ..................... Green
L ...................... Blue
O ..................... Orange
P ...................... Pink
R ..................... Red
Sb.................... Sky blue
EC612000
WIRING DIAGRAM
71
5
62
3
4
B/WB/W
B/L
B/Y
SbSb
G/B
LYLY
P
B
B
B
B
G
O
WR
P
GW
R PP
B Br W
W
B/YGBr
G RR
OB Sb Sb Y
Y
WY
W
GG
B
PP
Br BrR R
OL
B SbY LL
B/L B/WB/W G/B
B B
B/L L Sb
B/L
G/B
G/BB/Y
B/Y
B/W
O B/W
BrBr
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 - 2
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.
Throttle position sensorCDI unitIgnition coil
Pickup coilCDI magneto rotor

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)
Ignition timing
Thr
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