Yamaha yz250 2015, Owner'S Manual

Page: 161 / 174

6-8
THROTTLE POSITION SENSOR SYSTEM
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 COIL
1. Remove:
• Carburetor
• Mixing chamber top
Refer to "CARBURETOR AND
REED VALVE" section in the
CHAPTER 4.
2. Inspect:
• Throttle position sensor coil resis-
tance
Out of specification
→
Replace.
3. Inspect:
• Throttle position sensor coil vari-
able resistance
Check that the resistance in in-
creased as the lever "1" is moved
from the full close position to the
full open position.
Out of specification
→
Replace.
CHANGING AND ADJUSTING THE
THROTTLE POSITION SENSOR
1. Remove:
• Carburetor
• Mixing chamber top
Refer to "CARBURETOR AND
REED VALVE" section in the
CHAPTER 4.
2. Remove:
• Screw (throttle position sensor)
"1"
• Throttle position sensor "2"
Loosen the screw (throttle position
sensor) using the T25 bit.
3. Replace:
• Throttle position sensor
4. Install:
• Throttle position sensor "1"
• Screw (throttle position sensor)
"2"
• Align the slot "a" in the throttle posi-
tion sensor with the projection "b"
on the carburetor while the lever "3"
is held down.
• Temporarily tighten the screw
(throttle position sensor).
5. Install:
• Mixing chamber top
• Carburetor
Refer to "CARBURETOR AND
REED VALVE" section in the
CHAPTER 4.
6. Adjust:
• Idle speed for throttle position
sensor adjustment
Adjustment steps:
a. Set the digital tachometer to the
high tension cord.
b. Turn the throttle stop screw "1"
until the specified idle speed.
Refer to "ADJUSTING THE EN-
GINE IDLING SPEED" section in
the CHAPTER 3.
7. Insert the thin electric conductors
"2" (lead wire) into the throttle po-
sition sensor coupler "1", as
shown, and connect the tester to
them.
• Do not insert the electric conduc-
tors more than required because
it may reduce the waterproof
function of the coupler.
• Make sure that a short-circuit
does not develop between the
terminals because it may cause
damage to electrical compo-
nents.
Tester (+) lead → Blue lead "1"
Tester (-) lead
→
Black lead "2"
Throttle po-
sition sen-
sor coil
resistance
Tester se-
lector posi-
tion
4–6 k
Ω
at
20°C (68 °F)
k
Ω
× 1
Tester (+) lead
→
Yellow lead "2"
Tester (-) lead
→
Black lead "3"
Throttle position
sensor coil vari-
able resistance
Tester
selec-
tor po-
sition
Full closed Full opened
k
Ω
× 1
0–2 k
Ω
at
20°C (68
°F)
4–6 k
Ω
at
20 °C (68
°F)
Idle speed for TPS ad-
justment:
1,700–1,900 rpm
Tester (+) lead
→
Yellow lead "3"
Tester (-) lead
→
Black lead "4"