When the factory only built ATC 90s this was built.
Winter project for a few days winter of 1975 at the Honda dealer I worked at.
CR 250 frame. XL 250 engine and front end with the rear wheel laced to the front hub. MT 250 gas tank. CR 125 intake manifold. SL 350 header pipe. All salvage or warranty parts. Some stuff is a bit crude but I was 18 when I put it together.
The Honda service rep spotted it and rode it around a few hours.
A couple of weeks later he called and asked if he could bring someone to ride it.
He showed up with two R&D guys from California. They rode and studied it for about six hours then had to leave to catch the flight home.
They said there was talk of building a prototype sport atc but they didnt know if anyone would be interested in one but someone was interested enough to build one.