SC is the same as Magnum and ASP, they have a very sensitive low end needle and it is usually too rich. A rich low end needle will make that engine behave like yours. A friend of mine had the exact same problems on his Magnum XLS 52 and after I tuned the low end needle on his engine it ran fine and never stops. Gently turn in your low end needle (with the carb closed) and count the revolutions to see how far out it has been, on the 52 engines it needs to be at only 0.5-0.75 turns open from fully closed and I guess the 46 is very similar since it is basically the same engine, just a tad smaller. Use the pinch test to fine tune, it is a great engine once tuned right