trouble starting up.

[bergstrom25]

So, as of lately, my GZ250 is being a bitch on start-up. It takes a more than a few turns for it to start up, and once it does, I have to keep the throttle on it (and the choke at full) until it warms up in order to keep it from dying. When it does finally spark up, it does a slow chug-chug-chug until its running. I've know idea what it could be that needs adjusting (and it's kinda hard to describe). But once she's running, she's running until I'm where I need to be so that's good. Anything I can do to check/adjust this start-up issue? The carb is clean, and so's the air filter. Just had a new petcock put on it too.