"Making oil" as it is called, is a pretty common ailment with 4-strokes. Obviously either water, raw fuel, or both is entering the crankcase and floating the oil level up.
Determining where it's coming from is the first step.
Remove the two screws holding the fuel pickup pump to the block but leave the other two that hold the fuel pump components together in place. Then while squeezing the primer bulb tightly look for any fuel exiting the vacuum side of the fuel pump (Careful...don't let it squirt you in the face).
Report back with your findings and we'll take it to the next step.