Yes, that is how you adjust the mixture so the engine will run lean or rich. With the model running at full throttle, adjust the needle so the engine runs it's fastest and smoothest, somewhere around one to two turns out from all the way in ( don't tighten it too much when it goes all the way in). Next turn it out counter clockwise a little more until the engine is running a little rich, where the exhaust becomes more visible and the engine gurgles a little.