Oneway bearing slipping GS-11 engine

[waqr]

I have an old Kyosho GS-11 engine with a pullstart that has an internal bearing (called FD24 on Kyosho part no list) The problem I have is that if I take the bearing out and clean it it works just fine. It works fine until the motor starts but as soon as the motor starts the one way bearing stops working directly. It must be that it gets contaminated with fuel and oil as soon as fuel gets into the crankcase. This is really strange since this will be impossible to avoid since the bearing sits inside the crankcase. I have also tried to grind slightly on the shaft without and imrovements.

Do anyone have any idea what could cause this? Since the bearing works fine everytime I clean it it can`t be a bad bearing I think, could it be something else?