To take a different angle from what has been mentioned.

Nothing wrong with having to choke an engine to start it. If you did NOT let it warm up and you are lean on the low end (I like it that way) it takes time for it to warm up.
If it still runs rich in the air (4 strokes) it could mean a few things are happening. Positive pressure building on the diaphragm, to rich on high end, etc.