Hi I have a raptor 660 with a full exhaust and k&n with lid on. When I try to start it, it only idles on the choke. It Boggs when the choke is turned off. When it does idle, it backfires and I noticed that the headers were turning bright red. Would this be because it is getting too much fuel? What would I need to replace in the carbs to fix this? Floats? Jetting?