well, are they stock 26's, bored out stock carbs, or 28's? you would usually just go down 1 size on the main, if any. get it pinned wot, mid-high rpm range, and see what it does. if it starts to sputter, then go down in size untill it can hang up at wot no sputter, then do a plug chop. you shouldn't loose power going to the box. can you snap a pic of the carbs?,,,oh and some of that sexy bitch of a bike