I found that some of the off brand name harsher Oven cleaners work exceptionally well cleaning two strokes pipes. The foaming oven cleaner seems to work best, then just rinse it well with water and let it dry.
Also works wonders on aluminum parts and use a brush. But, you have to absolutely make certain that you wash them well with water and stop the chemical reaction once it's cleaned to your liking. But, they'll turn out like new once you scrub them with a wire brush.
Use gloves when handling the parts with the oven cleaner on them.