1980 muffler surface with black spots

[k2suzuki]

I need help. I have black spots on my mufflers, both left and right. It was clear nice chrome when I got the bike a year ago, but now, it has this black marks. Can anyone tell me why this is happening and how I can fix it? I think there might be a leak where exhaust leaks out and hit the surface of the muffler where it burns the surface. But what do I know. Please help me solve this puzzle. Thank you in advance for all suggestions.

[steve murdoch icoa #5322]

Looks to me like you're melting your boot/shoes on the muffler.
Autosol and some muscle should remove it. I wouldn't use an abrasive cloth of any sort.
You MIGHT have to use something like GooGone on the black first before the chrome polish.

[NobleHops]

I’d try an acid clean, with a dilute solution of Ospho or similar phosphoric acid product. Wet a paper towel with it, drape it on the spot, and after 15 min, see if it is dislodged. Or acetone.

[Jeff Bennetts]

That bike is ruined, better sell it before it gets worse.

[Larry Zimmer]

Boot rubber -- use acetone and non-scratch pads.

[k2suzuki]

I thought so too but I cannot find any issue on my boots.

[NobleHops]

Do you store the bike on the sidestand? Maybe it’s potting goo from the ignitors.

[daves79x]

Oven cleaner and 0000 steel wool, if more mild efforts fail.

Dave