If I don't shut off the gas it will leak on top of the engine. Is this normal?

That is typical of the carbs on these 2 stroke engines. It's always a good idea to turn the fuel valve off when not using the bike because the fuel continues to drain into the carb until it literally over flows. These carbs can only hold so much fuel until it has to find a place for it to go. Also make sure to tighten the small phillip head screws on top of the carb bowl and the one on the bottom side.

Some high temp silicone may be in order too!