Just bought the WT 433 and installed it on a Ryobi 31cc. The engine ran perfect right from the start. The line from the tank go's to the large diameter brass pick-up, the small brass pick-up is sealed off,( I use a piece of fuel line with a small bolt screwed in the end). This big bore carb pumps a lot of fuel for a 31cc engine. I run with the high speed needle almost closed and low speed 2 1/4 turns out. Fantastic low idle and instant exceleration. With the Jag Engines Muffler and the Wacker Engines Carb, this engine now sounds like a mean chainsaw engine rather then the wimpy weed-eater engine it use to be. The engine is not lean at this setting and after idling for a long period will put out a puff of smoke at exceleration. The one thing I did note is that if you put any part of the fuel-line above the carb ,creating a hill for the fuel to climb it will not draw. Keep your fuel-line a relatively straight line from tank to carb and you will have no problems. I am drawing more fuel than I need and am completely satisfied with this carb and will buy again. -Ron