Was gonna say brake dust at first, sounds as if you may want to re-tune your setup, my 2 cents!

 

I think you may have to wash your bike, though!

 

Maybe a silly question, but you did not say if the same soot was present in the end of your pipes, just curious. I get black soot all over the back of my bike, none in the pipes, I'm sure its break dust, or plain ole road dirt. Sometimes the trade off for a good looking ride is way to many hours cleaning.

 

Had the same problem with my 01 RK. I changed the exhaust to Supertrapp with turndowns and didn't pick up as much soot.

 

Most of it that I've experienced is exhaust carbon. The longer your muffler tips, the less black soot.

 

If you have black soot on the rear of the bike, it's likely running too rich. Gray dust is just road dirt. Black soot (along with the little decel pop you referenced) is a sign the bike needs a tuning. A well tuned bike will leave next to nothing on the back of the bike.

 

I don't get any such soot and I ride alot. I also only wash the bike about once a month at the most - so 2500+ miles or so of riding between washes. My bike is stock so most likely a bit lean (but shows no excess heat or pinging so I've left it as-is) compared to yours. Just a comparison here, so I'd say the posters above on are target that you're running rich. If this was brake dust I'd certainly have it on my bike.

 

Soot = tune.
dirt = dirt.

 

+1 brake dust

 

Agree.....brake dust