Some guys in Germany built this air-cooled, DOHC, 87cc V12. It puts out 8 horsepower on methanol and nitromethane. It was made to put into remote-control boats and cars. Just listen to it. And yeah, I know news of this engine first surfaced in 2008. Some things are just worth revisiting.
My only question is, could I strap it to my mountain bike?
Check out their site at WAWU.EU