If the lower end is full of fuel your needle and seat isn't seating properly. You have a constant flow of fuel coming out of the carb into the cylinder. The way it works is when the bowl of the carb is full the float raises up and pushes a rubber needle into the hole where the fuel is coming from. If there is dirt or something that can stop it from sealing fuel will comtinue to fill the cylinder. It will leak by trhe rings beacuse they only seal under a load, not whaen sitting still. Your ring are probably OK. You need to clean out the carb.
This man know's his sh!t, i bought a 250R from him a few months ago, good people.