I was running the bike out of fuel on purpose. Ride was over, bike washed and ready to be put away. Seemed like a good idea to turn the fuel off and run the float bowl dry. As the fuel level in the float bowl drops, the mixture goes lean. It sounded like it had a bad air leak or stuck throttle. RPM goes sky high until it runs completely dry. Kill button had no effect. Won't happen again.
Kawboy, I saw a Detroit started with an air filter that had been cleaned with solvent and not completely dried.
Runaway 2-stroke diesels in metal pole barns are memorable.