The Briggs 5.5hp is off my rototiller. Made a stainless intake manifold & mounted a Mikuni 22mm carb. Frame is electrical conduit I welded together incorporating an old Yamaha 100cc fork & steering head and swing arm. The lower frame member is also a glass packed muffler. Schwinn OCC wheels, disk brakes are from a pocket bike & various parts from 2 different bicycles.
With 6:1 overall ratio, 44mph is top speed. I will add electric start soon as "pull-cord" starting is a hassle without compression release. Overall, Im pleased with this one. It's a real hoot to ride!