MOPED ARMY

Could be a couple things.. the easiest thing to check is the float needle. Polish up the float inlet where the needle sits, and inspect the needle. The tip is rubber and if it gets deformed it can stick and not let fuel feed into the bowl and your bike is starved out after a short time.

Second thing to check if the carb is all good, would be that the condenser could have gone bad. That will require more tools and effort, but easy to fix. So give that carb a good cleaning first.