hey guys i got a fuel leak comming out of the tube at the bottom of the carby on my bike it will stop leaking when the fuel tap is turned off and the fuel empties out of the carby but when the fuel tap is on it just flows out. I noticed there was a screw above the tube and when i loosened it the fuel came out faster but when i tightened it up the fuel kept on coming out but a little slower. What should i do to stop the leak??