I'm new to these bikes and know very little about the engines. However, I'm a long time shadetree mechanic on cars. I would check the engine venting and make sure it is working appropriately. If pressure is building up in the oil pan, it will blow oil up to the intake. Perhaps you fixed the problem if it was stuck rings on that one cylinder. On a V8 car, one valve cover is vented to the air cleaner and the other is vented to the intake mainfold through a PCV or check valve. The purpose of the PCV is to prevent a backfire in the intake from blowing the oil pan off. Intake manifold vacuum pulls on the engine base through one valve cover and gets air from the air cleaner via the other valve cover. Our bikes have some system to do the same thing, I just don't know what it is.