Hi my xt 550 is a 83, runs on number 1 carb for like 5-10 minutes hoter than carp, then all of a sudden its run great very fast front end comes up, not so hot any more, revs very fast like it should, then I stop motor start it again flat like 1 carb is working getting hot again, whats wrong with my bike, carbs are very clean new cut off falve new neddle falve, help please. Dave Broude.