Mine wet sumps and hot idle is about 15 pounds pressure.
There is a small plate in the breather cavity, behind the triangular plate under the rear cylinder, with two bolts at the top of it. I believe that plate is designed to flex and open to allow oil to flow when pressure behind it pushes it open. When at rest it is closed, or should be. Mine sits on the part of the cade that is not a perfectly machined flat location and a wear mark can be seen on the side of the plate that contacts the case. If it were machined flat i bet the wet sumping would go away.
