MOPED ARMY

I agree. Remember that most of our engines are air-cooled with the exception of the Minarelli and a few fancy liquid-cooled Moby's, if no air is rushing past the cooling fins you'll overheat the engine for sure especially if it's something like ten minutes. I'm riding at night now with temperatures hovering around 12degrees Celcius and I don't let it idle for longer than 2 minutes.

I've never heard of the bump you're speaking off though, how does it form?