Jim, it is actually not a labyrinth. In a labyrinth the path is made longer because you have to go up and down, note the diagram on Wikipedia. In the Kawasaki center seal it is more like a hallway with little side rooms that allow the compression wave to expand and re-compress. There is actually very little oil that enters at this seal, and because it is wide open all the time, never enough to actually form a plug. I would have to get into the mind of the engine designers, but I personally believe that the center injection of oil is more a function of providing lubrication for the bearings on the sleds that have the extra shields on the crank. It is important to note here that the Intruder has the same seal but has no center oil injection and does not have the crank shields next to the counter weights. I think I should take some more photos.