I have the same engine, same aircraft. Although Patrick says 10#, I would check it, when you get your hands on it. Most people found the plane a little heavier than quoted, however the 140 hauls it around with authority and will hover around 60% throttle. The 140 is not pumped, it has a pressurized fuel system. First thing to check is that the fuel tank and lines are absolutely pristine. Although it will run in 15%, the more nitro you give it the better it likes it as the needle develops a broader tuning range and it develops more power. The YS importers recommend 20/20 fuel and I have used 30% heli fuel.