That looks like a DIY version of the old “magic can” fuel system. The can is just a reservoir to simulate a gravity feed like on a bike. One thing that seems wrong about the carb plumbing: the line looped under the carb, from side to side, should go over the top of the carb, and have an air vent snipped in the center of the loop. The way it is now, there is no venting of the float bowl. Not sure what that bottom hose is about, never have seen one of those on a shifter engine carb.