I took off the Harley Stage 1 AC from my 2010 Limited and replaced it with the Vance & Hines VO2 Naked air cleaner kit. The Vance & Hines breather tube design works much better in getting that little bit of oil that comes out the breather into the intake and not the AC. The oil used to just run down the Harley backing plate into the AC and after a while it would start dripping out of the AC, down on the motor, out back to the exhaust, pants and saddle bag. Looks like this design could be modified without much trouble to accommodate aftermarket breathers. Not as nice looking as the halrey AC but I can live with it.

 

What kind of oil were you using? I switched to Mobil1 when mine did that and it quit. I was using the Screaming Eagle synthetic CRAP before that

 

I have used Harley Syn and Redline Syn and it has happened with both.

 

That little bit of oil going into your intake is ending up as carbon residue that blocks off your exhaust ports.