Plenty about this conundrum on the Forum already. Any imbalance between oil supplied and oil returned will result in too much in the sump and out of the breather it comes. The return pump capacity is greater than the supply side, so the engine is designed to have a so called "dry sump" and under normal running the actual sump should contain very little oil. These engines tend to accumulate oil in the sump on standing, so some exhaust smoke and oil from the breather is to be expected on start up if you're unlucky. This normally clears after a few minutes running as the return side works its magic.
As a start get the sump plate off, check the gauze filter and pick up pipe tip is clear and that the ball valve is free. Stick a plastic tube over the pipe, blow gently......a lot of airflow indicates a leak, typically a fractured or leaky pipe or a loose oilpump. The pump /crankcase joint needs to be sound, the mating gasket profile for each oilway is marginal, and this area is critical. All will cause air rather than oil to be sucked. There should be a fair resistance if all is in order, you are trying to force air up the pipe, through the pump and back to the tank.
Then staring with a truly empty sump, try again. There will be little return to start with, then it should return with gulps of oil and air, then a good strong flow as the throttle is blipped. Folks have had problems with restrictions back to the tank and/or too much oil being fed to the rockers. This means more oil goes back to the sump, exceeding the pump capacity of the return side of the pump.
Most problems of this type can be overcome by a bit of detective work, not a major teardown.
Swarfy.
