2017 KTM 250 EXC AU Owner's Manual
TUNING THE ENGINE. If there is a big engine speed rise, 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, mount a smaller idling jet.
After changing the jet, start from the beginning with the adjusting steps. Following extreme air temperature or altitude changes, adjust the idle speed again. When driving, the shift lever must not touch the rider's boot when in the basic position. When the shift lever keeps touching the boot, the transmission will be subject to an excessive load.