This isn't a bike, but the generator in my RV. It runs, finally, and produces 120vac as it is supposed to, but the engine surges. I have had other single cylinder equipment do this as well, but never really worried about it on those (usually old lawn mowers). Any thought as to causes? Carb trouble is my first thought, this thing sits unused for great expanses of time. I did remove the carb , disassemble and clean it to the best of my ability with spray carb cleaner, and it looked pretty good. This was actually what got it running at all. If no other ideas surface, is it usually worth it to just replace, or are these small carbs rebuild-able with any success?