Thats a yamaha xt600. I know nothing else about it.Above photo seems more of a photoshopped big motor in a TW frame since front sprocket maps out at a point that looks to be in conflict with motor's flywheel and starter.
However actual TW wide 14" rear rims have been mated to bigger bikes like a few Yamaha 450 thumpers I've seen adds for, one at least with a paddle tire for sand. Lots more room on a full size frame to align sprockets in same plane if necessary via jackshaft , engine re-location, or the output shaft extension idea lie what we use on XT/ TTR225 conversions in our TWs.