I have used Semichrome Polish with great results. Black residue will build up on the material being polished...this is the old layer of tarnish coming off of metal. Works way better when you periodically wipe the residue away.
I've used Semichrome and XTreme....they are both good. I have to admit though, Mothers has worked the best for me. I use it on the wheels of my truck and the nickle plated shocks and it's the best so far. The Semichrome works really good on brass though. Either way, its hard work...have fun.....
I refurbished some aluminum forks on a Yamaha Venture that were yellowed..I simply sprayed some varnish remover on the part and waited a few minutes and wiped off the old finish. Then i would use some aluminum conditioner like flitz. Clear coat when done....Like new when done with very little effort.
Give Oconto Metal Finishing Inc. a call for info on having wheels polished. They do good work, and actually do some factory work for Harley on some of their show bikes every year. I know several guys with sport bikes that had wheels polished by Oconto and they look great. I remember something about solid disc wheels being the lowest cost to polish, then upwards from there.
Oconto Metal Finishing Inc.