I'm just finishing work on a 74 Commando Roadster I got recently. The bike ran okay but a bit rough when I got it. I cleaned the tank, carbs, plugs, new battery, brakes, rubber parts, cleaned switches, some rewiring etc.. (has Boyer ignition and a single MK2 Amal carb) My problem: Starts easy, usually one or two kicks, idles nice, runs strong at all throttle positions. Will go for 5-10 blocks usually (sometimes more, once went two miles) then it will quickly sputter and die. If I try to restart immediately, it wont but wait a couple min and it starts right up. Then the same thing over again....5-10 blocks and dies. I've looked at the plugs and they are black but not too "furry looking"....gas in new and clean....carb is clean...air mixture is one and a half turns CC from seated....valve were just gapped at .008 exhaust and .006 intake. Any suggestions and or a recommended approach to solving this would be really appreciated.