Carburetor - Adjusting Idle Speed - KTM 85 SX 19 Owner's Manual

15 TUNING THE ENGINE
15.4

Carburetor - adjusting idle speed

If, during acceleration with a partially opened throttle slide, the engine runs only at
stuttering performance, the jet needle must be lowered by one notch. If the engine
knocks, particularly during acceleration, when it is in the top-performance engine
speed range, the jet needle must be raised. If the phenomena described above occur
during idling or just above, the idling system is to be regulated more leanly during
stuttering performance, and less so during knocking.
Full-load range D
Operating with open throttle slide (full throttle). This range is affected by the main jet
and the jet needle.
If the insulator of a new spark plug is very bright or white after a short journey at full
throttle, or if the engine is knocking, a larger main jet must be used. If the insulator is
dark brown or sooty, a smaller main jet must be used.
x
–
Screw in idle air adjusting screw
position.
Guideline
Idle air adjusting screw
Open
–
Run the engine until warm.
Guideline
Warm-up time
L00074-10
Danger
Danger of poisoning Exhaust gases are toxic and inhaling them may result
in unconsciousness and/or death.
–
–
Adjust the idle speed with adjusting screw
Guideline
Choke function deactivated – The choke lever is pushed up all the way.
( p. 13)
Idle speed
–
Turn idle air adjusting screw
begins to fall.
–
Note the position and turn the idle air adjusting screw slowly counterclockwise until
the idle speed falls again.
–
Adjust to the point between these two positions with the highest idle speed.
Info
If the engine speed rises considerably, reduce the idle speed to a normal
level and repeat the above steps.
If the procedure described here does not lead to satisfactory results, the
cause may be a wrongly dimensioned idling jet.
If you can turn the idle air adjusting screw to the end without any change of
engine speed, you need to install a smaller idling jet.
After changing the idling jet, start from the beginning with the adjusting
steps.
Following extreme air temperature or altitude changes, adjust the idle speed
again.
all the way and turn it to the specified basic
2
When running the engine, always make sure there is sufficient ventila-
tion, and do not start or run the engine in an enclosed space without an
effective exhaust extraction system.
slowly in a clockwise direction until the idle speed
2
1.5 turns
≥ 5 min
.
1
1,400... 1,500 rpm
69