Turn it clockwise and screw it in all the way. This will give you excess slack in the cable and your throttle will have excess free play. Now turn it counter clockwise and screw it our or lengthen the cable. Take about one turn at a time and check the free play in the throttle. If you reach a point there is no free play in the throttle at all, you've gone to far. back it off a tad until you have a little free play. Once you are happy with the free play, start the bike. At idle turn the bars from stop to stop. If the engine idle speed increases you'll need to give it a bit more slack in the cable by turning the knob clockwise a turn or two.