I was wrong about those four stroke personal watercraft engines. The
Honda engine is rated at 137HP and the Yamaha engines are rated at 110
to 160HP. All of these are much bigger than you were looking for.

Tony

tffy wrote:
This is for a hypothetical ultralight design, so just looking for
suggestions here of where to look at... hopefully a 4-stroke, purchase
price doesn't matter much, certification status doesn't matter either.
Long time before overhaul matters A LOT... so, the longer the better.
Is there anything out there in the 80-hp range? How about a motorcycle
engine conversion - how long can those go before needing to be
overhauled?

Thanks!