At the bottom of each carb bowl, there's a little drain port, and on the side of the bowl there's a screw inset in the casting pointing towards the base of the drain port. Unscrew that screw to open the drain and see how much fuel, if any, comes out after the bike stalls. I recommend putting a small hose on the little nipple of the drain and direct the flow into a glass jar.How to I check if its getting enough fuel ? Why would it run fine for then just die ?
If they're empty, you're starving for fuel, which means there's either a restriction in your fuel lines (which would probably only lead to one carb being dry, not both) or the vacuum activation of the petcock is broken in some way, either a vacuum line leak, torn diaphram, or clogged valve.