I have a 1991 FLHS w/ 1340 evo I bought last summer from a private party. At first, it had the common "oil in the air cleaner" problem. Over the winter, I replaced all the oil lines with Goodridge stainless braided. I put in 3.5 qts. of oil, new filters, and went for a 10 mile spin. When I pulled into the garage, the right side was covered with oil. I removed the a/c, started the bike and watched as oil kept violently shooting across the garage from the breather and splattering against the wall, nearly emptying the oil tank. I think this is a bit more than "oily mist" venting to the intake for combustion. The oil lines don't seemed to be kinked. The sparkplug on the rear cylinder was oil soaked. (don't know if that problem is related) I'm new to HD and admit I'm stumped.

 

Even when replacing oil lines some oil will stay in the tank, and or crankcase on these engines. It is possible that adding 3.5 quarts was too much. Did you replace the oil filter as well? It sounds to me like too much oil in the bike.

 

It could be:

1. Too much oil in the bike to begin with
2The oil lines connected to thewrong fittings
3.The oil pump check valve could be stuck open. Thiswould cause oil to leak down into the crankcase and cause the bike to wet sump. Then your oil would remain in the sump and not return to the tank and you think you are low and keep adding oil until you have the oil pumping fountain you now have.

Just a guess but I'm guessing #3

 

If I recall '91's didn't came with head breather valves they had crankcase vents. so it seems over the years someone did some changes to the motor. if it was overfilled or the oil sumped into the crankcase, I would think oil would be flowing out the breather tube in the lower rear of the motor. now if they left the lower breather intact, and added head breathers that would make any blowby nonexsistent not worse. you have more places for crank pressure to exit the motor. I would pull the air cleaner off, start the motor and be sure the oil is comming out the head breathers and not a popped pushrod tube holder or somewhere else.

 

Are you sure? He said he did remove the A/C and oil was shooting out of the breather.If theoil pump check valve is stuck or dirty oil seeps by and goes into the crancase. Then when you start the bike it blows out the breather cause there's too much to fit through the return line all at once. If he just pops the big screw off the top of the oil pump closest to the crankcase (the inside one). Take out the spring and 1/4" ball bearing. Flush it out with brake clean and swipe it with a big Q-tip.

Note: Always run the bike for at least10 minutes before checking the oil to get the oil hot soall the oil will return back into the oil tank. Otherwise you risk overfilling it. A simply overfilled oil tank will also cause oil to blow out the breather.If you need a new ball the part number is 8873 and the spring is 26262-80 and both cost about $3.50

But I am pretty sure there is a ball valve on the 91. I know they chenged the pump in 92 but I am almost positive there is a valve on the 91. Hey Skip are you reading this? You are the resident evo expert here?

 

Yes, there is a ball valve...and I think it's not seating correctly. It keeps filling up with oil, telling me that the case is pretty full. The breather runs from the bottom of the case to the a/c. I have considered buying the kit to re-route it, but for now I don't believe that will solve the problem. I am going to try to empty the oil out of the case and clean the seat in the ball valve. Thanks for the great input so far!

 

If it has any scaring marks or scratches replace it and the spring for the $3.