Does it cut suddenly, like from the kill switch, or it bogs a bit before dieing? Do you have fuel? Reserve?
Sudden stop usually means electrical problem, while bogging must be fuel related. Since it did start, I vote for carb problem - most probably a clogged jet or something, as we don't have filters on these bikes and the tank is metal.
Try running it with the choke pulled up as the its jet bypasses all other jets. I had this issue once, and I "fixed" it by knocking the carburetor with a screwdriver handle. Apparently the clog dropped and it was all good.