On my 225 Dauntless I am running very rich on the left side bank. It idles fine but as you break the throttle open and hold it it starts to spit and sputter blowing and blowing smoke. I've noticed that the manifold is divided in two, left to right. I recently went through the carb, cleaned it all out, new gaskets and such. Near as I can tell I can't find any vaccum leaks.