I didn't want my first post to be a plug, but I think you guys might appreciate this. While looking for something to clean my bucket of rust at the local home improvement store, I came across Simple Green Precision Parts Degreaser. I've used SG before for welding prep and cleaning, but I've heard the drawbacks of using it on aluminum or on carbs.
This stuff is supposed to be safe on aluminum and other alloys and not leave a residue. Gotta say, I'm pretty impressed with it. Cleaned my crankcase covers with it and some 000 steel wool and they look pretty good. No residue, but certainly strips paint much better than regular SG.
I'll try cleaning my carbs with it today (hopefully) and see it handles that.