Powell Challenger Phantom 7 frame might fit that engine if the Briggs up draft carb is not in the way of the Powell's rear suspension spring. The carb could be moved with a straight manifold and a different Motorcycle type carb. Powell did have a front brake option I need to find 3 front brakes LOL . Powell's were made for a big engine and a full sized rider with it's big 8 inch wheels.
Steve
Steve
I have an 8HP in my bonanza with a TAV2 - Rear brake only though
I bought a Sears with a built 8HP Briggs in it for $125 but no front brake. The Boonie in the background fits an 8HP Briggs easy but no shocks and f brake.
There's a number of advantages to a sprung seat [sprung rider] over a swing arm [sprung vehicle and rider]. I know it might not be what a person expects to see when looking at a two wheeler with shocks. One advantage is a lot more room for things like engine, jackshaft and etc. They are lighter and have less mechanical complication. Chain tension is always the same and they are cheaper to manufacture. Plus the sprung seat provides a smoother ride than the swing arm. Try it out, you might like it.
I've seen them stuffed in rupps but you have to use the rupp tank. don't really see why that would be an issue thou. also I thought I herd something about having to lift the tank up a bit to have it fit right. I have also seen them in fox thunderbolts again using the stock fox tank. I even got to try one out. it made for an extremely powerful and fast bike.