ORIGINAL: Stick Jammer
I do not own any Tower engines but I have to agree with AGR413. The low speed needle setting will affect the mixture all the way up to wide open. They really should give this needle a new name because it controls much more of the throttle curve than just the idle. If your engine was loading up at half throttle, the low speed needle was most likely way too rich. Kinda curious though why you were only at half throttle for takeoff and climb out.
I own a tower 75 and use it on my Keecat 65. When I was breaking the engine in, it just did not want to run properly and no one could tune it. So, one day, I just decided to take a couple of turns out of the low speed needle and sure enough, that fixed the problem immediately. It runs absolutely perfectly now and I think its a great engine for the little money you have to dish out.