Low-speed Needle Tuning
Now, you can send your vehicle out again to run the engine and clear it out. This time, however, all you have to do is drive away from you at full throttle, then after about 100 feet, turn around and bring it back to you again at full throttle. Right away, reach down and pinch the fuel line and hold it so that the fuel flow is cut off. The engine should continue to run for about two seconds, then rev up slightly before stalling. If the engine dies almost instantly, the low-speed needle is set too lean. If the engine runs more than a few seconds, the setting is too rich.
The low-speed needle will also affect how the engine idles, so you may have to adjust the idle screw slightly to keep the engine running at idle.