I have an 08 Fatboy that was stored for about a month. When I got ready to ride recently, the oil dip stick showed empty. There was no oil under the bike and I had not had any leaking problems that I knew of up to the last ride. I refilled the tank and took off. Within half a block, the oil filler cap blew out and the extra oil was blown out. Obviously I had to return home and remove the remaining extra oil (did an oil change to make sure the oil level was right), clean the right rear side of the bike, remove the rear brake pads and clean them, etc. So.. is there some kind of check valve that is supposed to keep the oil in the tank from draining down into the sump when the engine is not running? How can I prevent this from happening in the future? Can't be good for the engine to crank up when the oil has drained down into the sump. The local harley guy said "just start it and warm it up before you check the oil". Any words of wisdom will be appreciated.

 

You've just experienced a common issue.

It's called "sumping" and there is a check ball located in the oil pump. The unit gets grimy and hangs up.

Service manual will point you in the right direction.