Sounds like you have a couple of problems with your carb.
First, sounds like you may be sucking too much air through that defective float bowl gasket. Air leaks can make starting difficult or impossible.
Second, the float needle valve sounds like it needs to be replaced. The float needle valve is attached to the float and is supposed to move upward and blocked the flow of gas when the bowl is full. The float needle valve has a rubber like pointed tip that becomes worn with a ring indentation and will no longer stop the flow of gas.
You can order these parts from Ike's Bike or Moped Warehouse or your favorite moped dealer