Gotta say it . Recheck the basics, including inspecting the exhaust for restrictions and testing the case for leaks. As previously mentioned, check the advance mechinism and operation of the points. I would also remind you to make sure the points fit the mounting correctly, sit flat and don't hit surrounding parts. Then I would start swapping parts side to side to see if you can isolate the offending component. Plugs, wires, coils, carbs and mounts.