We need more information to help you with your problem. How long are you letting your bike sit before starting it?
If it is more than a few days the fuel in the carbs can evaporate enough that there isn't enough to start the engine. Your bike has a vacuum petcock so fuel flow to the carbs stops when the engine is shut off and does not resume until air starts flowing through the carbs (cranking it over with the starter motor will do this) again to provide vacuum to open the petcock. And then it has to be open long enough to let the carbs fill, which can take a while.
If it has only been a few days you can usually use the accelerator pump to inject enough raw fuel into the throats of the carbs to start the engine. Whack the throttle open vigorously 4 or 5 times BEFORE you touch the Start button.
If it has been longer you can blow gently into the petcock's drain/vent line (small hose connected to the petcock between the vacuum line and the fuel line - exits below the bike) for a few seconds to open the petcock. Again, this works best if done before you touch the Start button.