Ben, I don't think the lack of need to use the choke has much to do with the engine being new. Chances are it's running a bit rich. The Honda carburetor does have a mixture adjustment as I recall (they call it the "pilot screw"), but the first steps are to ensure that the air filter is really clean, and that the choke is opening completely. Then try adjusting the pilot screw until it gives you the highest idle speed.
