It Is The Inner Crank Seals, The Only Way To Fix It Is To Replace Or Rebuild The Crank, The Oil Is Coming From The Oil Gallery Around The Rotary Valve. Iv Fixed Bunches Of These. Somtimes If The Leak Is Slow And You Can Turn Over The Motor With The Plugs Removed And Blowout The Oil And Get It Running And As Long As You Run It Every Couple Of Days It Will Burn Out The Oil But After A Week Or Two It Will Leak To Much To Burn Out If Its Not Run Often.