OPS are back, at least i think they went away, and have now introduced this OPS Super Track 14mm. This motor is a 3.5cc engine for, as the name suggests, circuit racing and the 14mm is seemingly important as it allows an improvement in the flow of the fuel mixture. What is also unique about this motor is that to save weight and in turn aid the acceleration of the crankshaft they have milled many small holes in the outer diameter of the small end side of the crankshaft. Doing this instead of milling the center of the crankshaft and adding silicone as is currently the norm, does a better job at reducing the centerfugal weight and therefore effects the performance more significantly.
You can view lots more pictures of the inside of the engine here.