If the bike has not been started in a while, your pilot jet could be clogged. I would start with cleaning out the carb and making sure every jet is clean and you can see daylight through the jets. Also, when the jets are removed, blow air through the orifices that the jets came out of to insure the orifices are clear. The gasoline blend sold here in Communist Kalifornia is only good for about 6-8 months of sitting before it goes bad. You can thank the EPA for that. :fft:
It's true that these bikes come very lean from the factory, especially the ones that are sold in Kalifornia. (You can thank the EPA for that too.) If the carb is clean and the problem still exists, try going up a couple of sizes on the pilot jet. If you are not sure which jet is the pilot jet, refer to your service manual or go online for an exploded view of your carb.