Yes, I would go through the carbs again. Follow the carb guide,
www.amckayltd.com/carbguide.pdf Pay particular attention to the idle circuits.
If everything is doing ok, when you start the bike use the PRI position on the petcock, this ensures fuel is getting to the carbs. Especially if left setting for awhile. Once it starts turn to the ON or RES position. In these positions fuel flow is stopped when not running.
The float valves are not fuel shuts offs, they are fuel metering devises. Even if they are working right when the petcocks are in the PRI position and bike is not running the carbs can over flow.
How is the battery? A low battery can make hard starting. The starter draws a lot of current, this can draw down the battery voltage low enough the TCI, electronic ignition used on your bike, won't fire the plugs. One indication of this is it won't start as you crank it but starts just as you let off the stat button. Once you let the button up the battery voltage goes up and if the engine is in the right place the plugs fire and the engine starts.
If your battery is low it maybe an old battery or a weak one. I would suggest fully charging the battery with a motorcycle type charger. One that has a 1.5 amp charge rate. Any higher such as one for a car and it can damage the battery.
Try with a fully charged battery and see if it starts better.
Leo