When the air is dense (which I doubt, because warm air "tends" to be less dense) you need more fuel, not less. I don't know what kind of engine you're running, or what carb, or what fuel, but it doesn't matter, when the air is dense, more air is pushed into the engine, and you need to compensate with more fuel. Without an air density gauge, you're just guessing anyway. Don't take this wrong, I'm not putting you down, I'm just trying to help. One other thing, if you go from a .052" jet, to a .053" jet, that's a 3.86% increase in fuel.