long story short, friend of mine has a Moto Guzzi w/the engine being gray/silver kind of like what the pc HD models have. Afte riding it for aboout 45 min w/me he grabbed a rag that unknowingly to him had rim polisher/cleaner on it and he went to town on his fins. Now they are yellowy/brownish color...does he spray them w/high temp paint or this there a cleaner out in the market.

Thanks for the help guys even though he's not a fellow HD rider....yet!

 

Try brake cleaner or engine degreaser...the degreaser first...or scrub with petrol...when the motor is cold of course!

 

I don't understand. Why would he paint them? Just clean and polish the fins with a metal polish like Brasso or Nevr-Dull.

It sounds like the rag was previously used on a different metal and that was burnished into his aluminum fins. It will take a bit of polishing (ultra-fine abrasive) to remove this thin layer of discoloration. This time use clean rags on it.

Perhaps a rag wetted with denatured alcohol will remove it.

You'll just have to experiment with the less drastic measures first.