so i built this project to save on gas.... a 6HP briggs and stratton powered skateboard. i built everything myself, and got this engine for it. engine fires right up first or second pull with the choke...but refuses to run with the choke open. i cleaned the carb thoroughly cleaning every jet and passageway with carb cleaner. put it together and stilll same thing. i checked and found that it is getting fuel to the carb. i can ride it with half choke..... but after a minute or so of riding it sputters, then dies. any ideas? this is very frustrating to me!