I would agree with britbrat. It sounds as though the low end needle valve is too lean. There should be info in the directions on how to check if the low end needle valve is set right. Generally you get the engine to sit at idle for a little bit and then pinch the fuel line. If the engine dies immediately it is too lean, if the engines does nothing for a while and then speeds up and then dies it is too rich. If it sits for a second or two end then starts to die you are ok. Get some one with some experiance to check it out for you. Also it may not be broke in all the way. The directions and experiance says that the engine should be broke in after a few three-four tank fulls, but some engines take longer. that might be something else to look at.