Why is there gasoline in Crankcase on 1981 Goldwing gl 1100?

The only way gas would be able to get into the crankcase is when the engine is off, gas is leaking down thru the carb's and passing thru the rings into the oil. Does the engine run well ? Is there always gas in the oil, or did you have trouble starting the engine and flooded it. If it was flooded once, that would do it. Change oil and filter.