Yamaha YZ450F(D) Owner's Service Manual page 191

HANDLING NOTE
Do not loosen the screw (throttle
position sensor) "1" except when
changing the throttle position sen-
sor due to failure because it will
cause a drop in engine perfor-
mance.
CHECKING THE COUPLERS AND
LEADS CONNECTION
1. Check:
• Couplers and leads connection
Rust/dust/looseness/short-circuit
→ Repair or replace.
CHECKING THE THROTTLE
POSITION SENSOR
1. Inspect:
• Throttle position sensor resis-
tance
Out of specification → Replace.
Tester (+) lead → Blue lead "1"
Tester (-) lead → Black lead "2"
Throttle po-
Tester se-
sition sen-
lector posi-
sor coil
resistance
4–6 kΩ at
20°C (68 °F)
THROTTLE POSITION SENSOR SYSTEM
2. Inspect:
• Throttle position sensor variable
resistance
Check that the resistance in in-
creased as the throttle grip is
moved from the full close position
to the full open position.
Out of specification → Replace.
Tester (+) lead → Yellow lead "1"
Tester (-) lead → Black lead "2"
Throttle position
sensor coil vari-
closed
CHANGING AND ADJUSTING THE
THROTTLE POSITION SENSOR
1. Remove:
• Throttle position sensor coupler
2. Remove:
tion
• Screw (throttle position sensor)
"1"
kΩ×1 • Throttle position sensor "2"
Loosen the screw (throttle position
sensor) using the T25 bit.
L Y
B
Tester
selec-
tor po-
able resistance
sition
Full Full
opened
0–2 4–6
kΩ×1
kΩat kΩat
20°C 20°C
(68°F) (68°F)
L Y
B
7-7
3. Replace:
• Throttle position sensor
4. Install:
• Throttle position sensor "1"
• Screw (throttle position sensor)
"2"
• Align the projection "b" on the throt-
tle body with the slot "a" in the throt-
tle position sensor.
• Temporarily tighten the screw
(throttle position sensor).
5. Make sure that the throttle grip is
in the fully closed position.
6. Install:
• Throttle position sensor coupler
7. Connect the FI diagnostic tool.
(Refer to "CONNECTING THE FI
DIAGNOSTIC TOOL".)
8. Set the FI diagnostic tool to the di-
agnostic mode, and then select
diagnostic code No. D01. (Refer
to "SETTING THE DIAGNOSTIC
MODE".)
9. Adjust the position of the throttle
position sensor so that the angle
displayed on the LCD of the FI di-
agnostic tool is 12–21°.
10. After adjusting the throttle posi-
tion sensor angle, tighten the
throttle position sensor screw "1".
Tighten the screw (throttle position
sensor) using the T25 bit.
Screw (throttle position
sensor)
3 Nm (0.3 m•kg, 2.2
ft•lb)