I am not trying to be disagreeable, but my money would be on an airleak or your airbleed screw was way off after working on your carb causing a lean burn condition and that the rind damage was due to the 30 seconds of run time at extreme RPM and lean condition. It does not take long to take apart a piston and rings under those conditions. This is why you should NEVER start a motor without a chain on it and be able to let the clutch out to kill it. I have a friend that has a race shop and has had customers call and ask what to do when he can hear a jet ski or snowmobile in the background running at redline. The best and quickest way to kill in that situation is turn off the ignition and put the bike to full throttle, the additional fuel will richen the mixture and stop the detonation.