Actually, Suzuki had a rotary motorcycle that did not sell
well. It was a relatively large bike and had a very unusual look.
Evinrude outboard company (actually OMC, the parent company)
made a rotary outboard and beat everyone by a mile in a race.
They banned the engines because they were so fast and not considered fair.
I remember seeing a 10-hp Sachs Wankel “MAC 10” outboard in a shop in Mississippi. Mid-1970s, I believe. I think the shop went bankrupt with that motor still in inventory (German-Italian outboards weren’t big sellers on the Mississippi Gulf Coast).
No kidding? If I could get one of those outboards on a bass boat...I’d love to try it out on Lake St. Clair.
OMC would have probably pursued the Wankel designs for ordinary consumer use, but by 1975 or so EPA was already making noise about wanting to regulate emissions on outboards. It was also around that time that those Kawasaki 2-stroke street bikes began coming up against bans in California, so the regulation death-spiral had already begun.