KTM 50 SX Repair Manual page 112

31/CARBURETOR
110
Info
If the speed rise is too high, reduce the idle speed to a normal level and
repeat the preceding 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.