my big red has a carb issue.i have rebuilt it including changing the slide tube pressed in the carb body. my needle is on the middle knotch where it should be.the mixture screw is 1.5 turns out and i still have a dead spot in the throttle.jetting is stock has a uni filter and stock exhaust. if i ride it and get on it it bogs but if i pull the choke up some it takes off. do it need a larger main jet ? kinda stumped here.