Wet sumping..something I thought was a speciality of old parallel twin Triumph motorcycles.
If too much oil drains into the sump if can cause major problems, on a Triumph.
The cause was normally a faulty non return valve in the crank case oil pump. The answer was either an engine strip down to repair the pump valve, qite costly, or put a stop cock valve in the oil return.
The latter solution was cheap and worked well, as long as the owner remembered to turn the oil on before starting.
Failure to turn on the oil alse resulted in an engine strip down, but in this case a rather more comprehensive and expensive re-build.
I don't know anything about the S&S Oil system, but I suspect it shouldn't wet sump.
