I was checking the front tire pressure on my bike after it was idling and melted the elbow protector off my jacket on the header... (Stupid I know) it's been about a month now and it's almost gone. I find I can smell it when idling in traffic when 3 or 4 bars are on the temp gauge... But that one spot on my pipes is gleaming silver not one bit of tarnish on it. (Coat your pipes in plastic and if ya don't mind the smell they will keep nice and silver...lol Not!!!) I tried to get rid of it to no avail, you may just have to let it burn off... If you’re careful you can scrape the majority off it off with a razor but watch that you don't gouge your pipes. This may shorten the process a bit.