Unfortunately installing only the cover on the breather still doesn't help from the oil thrown onto paper filter element. The internal space should be staffed with something that catches the oil. In that case you need to install either the second screw (which is extremely difficult), or make the cover with a little tail, partially inserted into the crankcase vent intake. How to deal with separated oil? The following is my post from the different thread with more details.
By the way, it took me 15 minutes to cut it out from the piece of plastic.
------------------
Let's begin with the air filter and a crankcase vent. As appears, it doesn't have proper oil catch breather. That is the reason why many people complain about oiled paper element. It is pretty clear from the pictures how to fix this problem.
Made plastic cover.
Stainless steel dish scrubber used for the filling.
Clean the drainage hole. Remove stock cap from the opposite side of the hole and install the purge tube.
To make the purge tube, hit the end of the silicone tube with a lighter, than quickly grip it with cold pliers (don't press too much). Hold it for 10-15 seconds, cut excess.
When the bike is on the side stand, the oil slow drips from the oil catcher into the purge tube. It should be cleaned periodically.
