Clintons! I really thought I’d never see mention of this engine name on FR.
Grandfather had a Clinton riding mower and a Clinton chain saw that was heavier than a dead preacher...and louder than a live one.
Clintons were a pretty common, inexpensive "minibike" and "go-kart" engine back when I was a kid. Back in the early-to-mid 60's, we would go to the dump - er, "landfill" - and there would be a pile of old powered reel-type mowers with Clintons and REOs and such, the engines salvageable but the mowers not so much.
Looking back, those powered reel-type mowers were kind of scary.