closing the thread. someone on another forum gave me this answer, which is similar to one i found here, but more detailed. very helpful. "...so in carburetors there’s big key called velocity and when you go bigger in carb size you lose velocity unless carb is of appropriate size. Bigger carb is better for reaching higher Rpms being stock carb is limiting factor. Considering high torque cylinder is low rev it’s better setup with small carb better velocity and considering high torque makes power down low rpms it better suits a curcuit which is low rpm torque pipe"