I just bought a 70 FLH and I don't know the history on it.... It sat for 4 months before I bought it. The oil tank was empty - added oil and tried to start it.... It started then died, and one to two quarts of oil slowly made a mess from the crankcase breather line......
Do I need to perform the check valve ball replace / reseat drill that I have read about on this forum?

I'll post a pic of this bike and my 78 FLH that I've been riding these past 7 years....

 

The reason that the oil came out is quite common and simple. Yes you will need to fix the check valve. This happens alot on EVOs. The oil that was in the tank was now in the crankcase. When you added the oil and started the bike, the new oil "puked" the old oil out. Drain the crankcase and the tank fix the checkvalve. You could potentially hydrolock the engine, where the crankcase is full of oil and as the engine turns it compresses the oil and the pressure needs to go somewhere, if it can't go out the breather, I've seen piston rings, seals, and even the cases crack. Not to scare you but show you the real problem is not the oil on the ground. Hope this helps.

npedersen2

 

Pull your spark plugs out, and crank the engine for a while, weather it be with a kicker or elec starter. this will get most of the oil out of the case.

when you are satisfied that most of it is out of the enging, i.e. the engine turns much easier, then go ahead and start it up. keep an oil pan under the breather hose during all of this, as oil WILL come out

this is very common, and fixing the check ball may not do anything for you.
ride the bike at least a couple times a week, and if you still puke oil, then go ahead and do the check ball fix, but if there is little to no oil out of the breather when ridden regularly, don't worry about it.

I've seen bikes with BRAND NEW PUMPS sump like that after sitting a couple of months.
another thing you can do, if you are going to let it sit, is to pick up a fuel line clamp, at autozone or the like and clamp the feed line when you park the bike, JUST REMEMBER TO TAKE IT OFF BEFORE YOU START IT!!!!!!!!