As w8ye said.
Sometimes the carbs are a little tight (Too much precision :-') and
I put a little oil on male portion, stick it in the engine portion and work
it around a little until it is halfway free. This helps to assure I have the
carb seated when I tighten it up. Make sure you get the cinch bolt good
and tight also or after several flight they will work loose. Another little
thing I do is to clean all the oil etc off the top of the carb and put a dab
of expoxy over the little throttle barrel screw on top. I have had a couple
of these come out over a period of time and this seems to prevent it.
Your gonna love that engine