Interesting Burn Pattern

The BFW Maxi wasn't running too well recently, and it was making a terrible squeaking noise from the magneto side. After pulling it in for service, I noticed a few things. The chain was super crusty and stiff, and very lose. New chain solved that problem. The clutch bell was trying to escape, and the outer circlip had come off, but was trapped by the clutch. The piston had this really gnarly stuff growing on it.
It seems like some kind of rust that might be running through the engine from the gas tank that is causing this weird carbon texture, but it remains a mystery. Some of that stuff was in the lubrication channel for the bearing, but it seems to be no worse for the wear at this point.
Also, since the Wizzard and I have taken that step in our relationship by moving in together, it left a small space open in the building which was promptly snatched up by some other moped lovers, and now right next to Responsible Jon's DeLuxe Powdercoat is this wonderful little space.