Been working this problem for a year now off and on. A little history...last spring when I got this K1 I went over the entire bike with the usual points, condensors, plugs, caps, timing, valves, etc. Deracked the #7A carbs and soaked in Gunk carb cleaner, added new 120 jets and new 40 slows. Cleaned the needles and left in middle postion clip. 26mm floats and new float needles and seats. Air screw 1 turn out. Bench synced and then Morgan synced. Tank Red Coated and clean. Standard air box with OEM filter. So I did the stuff you would ask and here is the problem: the bike starts and idles perfect and runs like the wind at all speeds. But when I am at about 50MPH+ and try to hold that speed I can feel a loss of power. At the lower speeds no loss of power...only about 50 and holding is when I can feel a slight miss. If I goose it at 50 or 60 she takes off good. Only trying to hold and cruise a higher speed I notice the loss of power. Moving the choke around at that speed makes no difference with the problem. I have the carbs off again to try to find this problem. I did check the small holes opposite the air screw holes and they are clear when I blow through them with the straw from the carb cleaner can. A side note, when decelerating I do get some backfire and small puff backfire only on #1 exhaust when sitting at stop light. I do have another rack I may stick on, but would sure like some tips on what I may be missing here.