We all know that the 50 and 125cc roadracing bikes has 2 stroke engines rigth?
Yes today this is truth but back in the 60`s Honda made some really sick 4 stroke engines with all of the high perf solutions we see to day.
Like dual overhead cams and 4 valves in each combustion chamber.
But think about the size of the engines.
The 50cc was a 2 cyl V engine and was rated to 15hp at 24000rpm
The 125cc was a 5 cyl I engine and was rate to 34hp at 22000rpm
They also buildt an 250cc straigth 6 but i have no numbers on those