Jaroslav Falta's 1972 CZ 250cc air cooled two stroke. The fin design was an attempt to create more total surface area for cooling. You could shift without the clutch, they designed the trans to take the abuse and for quick starts since before starting gates everyone on the starting line had there left hand on there helmet, the CZ guys could jam the bike into first gear and go, and get the hole shot.
Doug Henry was scheduled to race this event last year, but couldn't make it due to the fire that destroyed his house. He's in this time around, and watching him motor around is awesome, and he's not messing around. He flies!