I have a 4 hp Briggs that is on the Model 404 Tote Gote that my students put together for the build off. The engine ran great on the bench. Since it was installed into the bike it will only start with full throttle and will only run with full throttle but it runs like it is holding back and smokes quite a bit. If I let of the throttle the engine dies. I checked the choke and the throttle and everything seems fine. It seems like it is something easy but I can't think of what it might be. I don't know a lot about Briggs engines. Does anyone have any suggestions?