My bike has always had that same problem. Ive changed carb setups 3 times and it always happened. the way i fixed it on the last 2 carb setups was i put my clip on the needle all the way down and it was almost perfect. I can stab it from a stand still and she goes. Contacting a builder is the way to go. cascade innovations in boring oregon did my motor. There are several in our area. White knuckle, redline, and a few others. Im starting a shop up here in longview but im not ready to do the major motor stuff yet. Im still learning also. personally i would call chris at cascade and talk with him. he'll help you trouble shoot over the phone. good luck. :cool: