BTW Dave, A word of caution... That star screw is actually a TORX head. Sorry, but I don't remember off hand right now which size. BUT , make sure you use the correct size driver..... AND do not strip the head! That screw is going to lock in the setting when it's tightened. So you want a good straight shot , with your driver as you tighten it down. On my bike, I have found that I need to move the battery out of the way, and to the right a little to get a good angle....... Tight, but don't murder the screw, so as to not strip the head.
If it is not tightened down correctly ?.... it will move from vibration. And so will your voltage reading. Then you will go TOO rich, or TOO lean......