I was wondering, Since RB's C10 (flasgship onroad engine) has the same specs as the 35 plus 21, and novarossi went back to the 35 plus 21 engine for the flash 21.
Does that mean that the 35 plus 21 is the optimal design?
9 ports, 14.5mm crank, 16.26 bore x 16.80 stroke.

Seems like they got it right with the 35+21 and don't know what to change?