Eagle 1 wheel cleaner for uncoated wheels for taking out stains and Greased Lightning for general extra heavy-duty cleaning have both worked well for me. But, rinse, rinse...rinse, rinse... The wheel cleaner contains phosphoric acid so you can take it from there. Be careful, though, I have found that on some of my bikes it turns some assemblies darker than others. Where the engine might turn out a nice "white" color the tranny may have a "grayish" tint to it. Still, this looks considerably better (in my opinion) than stains... Others use Simple Green and Scotch Brites, WD-40 and Scotch Brites,