Hey guys.  I'm a carb rookie.  My choke used to work and it was great for cold starting.  After replacing the head gasket, cam chain and a few other things (nothing carb related) the choke doesn't work anymore.  Cold, the bike just won't start with the choke.  After it's running I can pretty easily kill the engine by barely pulling out the choke.  I've fiddled with the idle mix screw and left it pretty close to its happy medium of 1.5 turns out.  Everything is stock on the bike.  

It has been pretty cold.  30 degrees Fahrenheit on cold days.  Today it was 50 and it took me about 3 or 4 minutes of trying to start it without the choke before it idled consistently.  It still wouldn't start with the choke out.  I've noticed that it starts better if I give it about 1/2 throttle with the choke in for a second after pressing the start button.

Any ideas what the problem could be?  I plan on taking the carb out and cleaning it anyway, I just wanted to know what to be looking for.

The battery works pretty well.  It charges well when I drive.