there could be a few reasons the bike is having trouble running, how long did the bike sit without starting? A simple thing to do would be to adjust the idle slightly, but that may only mask the real problem.
You may want to simply drain the sediment wells on your carburetor, and see how much sediment there is in the gas that comes out, this might solve the problem right there. I had a similar problem a few weeks ago, and this cleared it up, temporarily, if there is much sediment, it's probably rust, and likely from the gas tank, so take a look inside the tank to see.
What fixed the bike for me was a combo of cleaning the entire sediment wells and retuning the carburetor.
hope this helps
Also, simple stuff, make sure the gas switch is in the on position. and when you clean the sediment well, put the bike on the center stand, as this will completely drain the well. And, when your done with the sediment wells, make sure to prime your bike, so there is gas in the carb again. finally, MAKE SURE YOUR GAS VALVE IS OFF OR THAT GAS WILL NOT COME OUT OF THE WELL WHILE YOU ARE SERVICING THE BIKE! this could be a mess and a huge fire hazard