[stretchwithme]

Maybe the new design solves the problem traditional 2 strokes have that makes them pollute so much. The intake and exhaust valves are both open at the same time, which puts part of the fuel right into the air.

I can't really tell from the flash movie on the ecomotors site whats happening with the valves. I do see some slits that could serve as the intake port when the cylinder is fully open. And a tiny round thing which could be the exhaust port sits at the center of the cylinders length. Maybe the exhaust port is electronically operated and is closed by the time the 2 cylinders open as far as the intake ports?

[sliverstorm]

Actually, making a 2-stroke that doesn't require both valves be open solves two problems. There's the fresh gas flowing right out the exhaust, and there's the limitations in compression ratio. Higher compression ratios result in higher efficiency, but the 2-stroke doesn't work right at high enough compression ratios.

Observe:

2 stroke: http://www.yamaha-motor.com/sport/products/modelspecs/30/0/s...

4 stroke: http://www.yamaha-motor.com/sport/products/modelspecs/12/0/s...

As a side note, do not conclude overlap (both valves open) is inherently bad. A little bit of overlap is sometimes used even in passenger cars.