Saw. Had to share. From the sale price, I'm assuming it's one of those 'ambitious, but rubbish' projects. https://akroncanton.craigslist.org/mcy/d/wadsworth-1991-cr80-dirt-bike/6768886671.html
Fresh link and screenshot. https://akroncanton.craigslist.org/mcy/d/wadsworth-1991-cr80-dirt-bike/6791151744.html
Doesn't look like it. Most of the Sachs Wankels I've seen on bikes were mounted longitudinally with a huge transmission housing. ArcticCat put some in snowmobiles in the early '70s and those were likely mated to a variable belt drive...also a large component. If anything, a sprocketed centrifugal clutch might be made to fit.
Probably a rotary lawnmower engine. Back in late 70's/early 80's one of the snowmobile parts distributors used to sell Sachs cores/warranty returns/old stock for pocket change.