My Saito is inverted and has never leaked thru the carb after several months of use or kicked back, thrown a prop etc. We all know the pros and cons of asthetics when choosing the position of an engine and the results anytime you put the carb below the fuel tanks outlets. My original question was about a flapper valve which stops pressure loss in tank from going back out the pressure tube when at low throttle settings. JrJohn replied, and I thank him for that, but did not extend a reason as to why it won't work. Has it been tried? Does it hold too much pressure? I just thought I'd throw it out there before I try it. Thanks for everyones input so far. Joe
P.S. Rocketman, it runs great as stock.