Small Engines (Lawn Mowers, etc.): Honda 110cc mower, honda engine, fuel jet

Question
small Honda engine plastic carb. runs super rich (i think) and therefor slow and rough.. gaskets replaced, seemingly clean parts within bowl, float integrity good.. new plug, appropriately gapped..   My main symptom is that if I turn off the gas valve from the tank to the carb bowl.. after about 20 seconds it will run like a top for another 10 to 15 seconds.. I assume what is happening is that the bowl is emptying until at the lowest point it isn't flooding anymore and runs well till out of fuel.. i assumed this was sinking float but that seems ok.. ideas welcome.. thanks.. governor?

Answer
Have you had the mower for a while?  Does the engine run better with the air filter off? Is the main fuel jet brass?

Have you used air from an air compressor to blow out all the carb orfices.  It is possible one of the carbs air circuit is obstructed.

Let me know the responses to the questions above.

Thanks.
Eric