I was taught this way.

[Rooster1971]

If I remember right, horsepower was indeed a measure of a horse.
Looked it up.
James Watt calculated that one horsepower was equivalent to one horse doing 33,000 foot-pounds of work in one minute. To better understand this—and avoid unhappy memories of arithmetic class—picture a lone horse raising a 33-pound bucket of water from the bottom of a 1000-foot-deep well in 60 seconds. That amount of work equals one horsepower.
With so many variables involving HP in engines because not every horse can operate at the same pace and longevity, I can kind of understand why small engines have gone to CC's Vs hp. New learning curve I guess.
I can quote factory HP by CC on motorcycles all day long, but the lawn care people that build mowers won't tell you HP.

I always thought CC meant the displacement of a motor. Of course we all know displacement not always equals more HP in combustion engines. In electric motors 1Hp is around 748 watts if I remember correctly. In my field the smallest fractional motors in some of these really small units are actually referred to us as watt motors.

 

[dennishoddy]

I always thought CC meant the displacement of a motor. Of course we all know displacement not always equals more HP in combustion engines. In electric motors 1Hp is around 748 watts if I remember correctly. In my field the smallest fractional motors in some of these really small units are actually referred to us as watt motors.

Named after James Watt that came up with the HP calculation.
Your absolutely correct. 250CC can be anything from 18 to 48 HP depending on two stroke, four stroke, porting, valving, and a host of exhaust upgrades.
Been down that road racing dirt bikes, and finally 250 R three wheelers for many years.

 

[Shoot Summ]

Been down that road racing dirt bikes, and finally 250 R three wheelers for many years.

Air cooled and/or water cooled?

We had 4 250R 4 wheelers, 2 boys racing, I've spent a lot of time in those motors. My Wife was the hold out, she rode a Banshee...