In 1984, Suzuki brought this quadraphonic chainsaw massacre to the road-going 2-stroke hypersports battle. The RG500 was a nimble bike, but roars onto this list because of its loony motor. It has four pistons, two crankshafts, and rotary valves to help capture the intake charge. The front of the bike looks looks tame, but four awesome pipes pepper the back and dump clouds of two-stroke on anyone lucky enough to be nearby. It might not be the only bike ever with a square-four engine or rotary valves, but it's hard to think of another.