Black filth
#1
#2
Simple, you need to open her up more to clean it out. It's probably corn cob build up from the crappy fuel these days.
#6
#7
#8
#9
With that said, That's what may be causing it. I have seen other bikes with super Trapps that look like the post combustibles build up in the disks. The exhaust is dispersed 360° through several disks and you don't get a high enough flow to keep it clean at low RPM. I think it's normal.