Currently MotoGP is 990cc. That will be changing to 800cc. Superbikes must be based on current production models and are limited with weight restrictions and other things. MotoGP bikes *cannot* be based on anything production, and the only other restriction is that they must now be 800cc. They are the ultimate racing machines. Essentially, what the factories are bringing to the table is the best, fastest, most advanced thing that they can dream up that fits in the displacement limit.