Oh no... Don't get me started on the BigWheel, or it'll be a whole new forum!.....
THX for the info on the spacer thing. I'm attacking it tomorrow.
Okay- the Briggs is from Goodwill, and the original carb had a worn out (loose) throttle shaft.... desparate to go riding on my day off, I threw a FlowJet carb from a 3hp briggs on it, and bungied the gas tank to the top of the seat. It worked pretty good, but hitting bumps and cornering seemed to cause the carb to do weird things....
Since then, I found another VacuJet carb (original type) for it and got rid of the UberCustom fuel tank set up. The muffler is different also. It has to extend pretty far back, otherwise the exhaust heat curls back up behind you at speed. Since then, I've welded an exhaust tip from a VW beetle onto a pipe and screwed that into the engine, and it flows good and sounds meatier than the Savage does (for now!) Sort of a mini glass-pack for Briggs!