No, I don't have any such fueling valves. The last YS had to be serviced and it was confirmed to be a problem with the engine. I have had many, many engines, and the two YS engines I have owned both have had this surging problem. To me this means that since YS is for high-performance, their engines are probably more finicky - kind of like owning a Ferrari - you get lots of power but you must baby it. I decided to go directly to YS for support. I am fairly certain my tubing or tank setup is not causing the problem.

Thanks for your advice.