KTM 250 SX 2019 Owner's Manual page 114

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16 TUNING THE ENGINE
Idling jet IJ
The idling jet has the greatest influence in the low to mid throttle slide range.
If the engine stutters when idling or accelerating with a partially open throttle slide, a smaller idling jet must be
used. If the engine knocks in this power range, then a larger idling jet must be used.
Idle air adjusting screw open ASO
The idle air adjusting screw has the greatest influence during idling.
Influence of throttle slide adjustment
The idling jet has the greatest influence when the throttle slide is closed. The first cylindrical part of the needle
and the clip position have only minimal influence.
When the throttle slide is 1/8 open, the first cylindrical part of the needle, the idling jet and the clip position
have the greatest influence.
When the throttle slide is 1/4 open, the idling jet and the clip position have the greatest influence. The influence
of the first cylindrical part of the needle is less.
When the throttle slide is 1/2 open, the position of the needle has the greatest influence. The influence of the
main jet and the idling jet is only minimal.
When the throttle slide is 3/4 open, the influence of the main jet is greatest. The clip position and the idling jet
have only minimal influence.
When the throttle slide is fully open, the influence of the main jet is greatest. The clip position and the idling jet
have only minimal influence.
Needle overview
The jet needles available are shown in the following table.
112
1
/
3
4
/
1
2
/
1
4
/
1
8
0
1
/
3
4
/
1
2
/
1
4
/
1
8
0
1
/
3
4
/
1
2
/
1
4
/
1
8
0
1
/
3
4
/
1
2
/
1
4
/
1
8
0
K00495-01
1
/
3
4
/
1
2
/
1
4
/
1
8
0
K00496-01
1
/
3
4
/
1
2
/
1
4
/
1
8
0
K00497-01

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250 xc 2019300 xc 2019

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