Bill Daniels wrote:

These are liquid cooled engines so with a large enough radiator, you could
keep it cool. I think motorcycles do run at higher percentage power than
automobiles - they have a far worse Cd.

Bill Daniels

The cooling systems on motorcycle engines do not have sufficient coolant
flow to keep the head from over heating under prolonged running at 3/4
to full output. The water craft and snowmobile engines may have better
flow but these also have access to lower temp coolant.

Honda makes a personal water craft that has a hot little 4 banger engine
that I thought might do the job. It would take some testing to see what
it's sustained power level would be.

Tony