Harley uses these umbrella valves in the head vents. I believe when they first implemented the umbrella valves they eliminated the timed breather gear. They run a dry sump so the scavenge pump and crank scraper tend to depress crankcase pressure. The timed breather gear acts as a one-way valve of sorts. I think when they incorporated the umbrella valves in the rocker boxes they ditched the timed breather setup (it was complicated). I don't think that particular innovation eliminated the constant puking all over the air filter and right side of the engine.
But the umbrella valves fit the bill for me, and I have a plan to try and fabricate a check assembly using the Harley umbrella valve. Wish me luck.
My Burgman uses a reed valve in the head vent. Nothing comes out of that. Its a 650cc twin with a 360 degree crank, so both pistons move up & down together. The reed valve assembly for that is compact so it might be a good candidate and probably sized correctly. The Burgman redlines at 8500.
Hayden makes a device called a "crank vent plus".
https://www.revzilla.com/motorcycle/hayden-krank-vent-plus-crankcase-breather...It looks to be about perfect in terms of size. If I get nowhere with my umbrella valve project maybe I will resort to the Hayden product.
For now, the catch can is working fine. I went out this morning for four timed pulls and a detonation check. The timed pulls went well and there was no hint of the dreaded spark knock with 98 octane fuel. I threw in a 7200 rpm 4th gear pull just to put icing on the cake. It ran fine and the vids look like its starting to run a bit leaner. Pulling all the excess oil out of the filter element. It's about an eight-mile round trip to my closed-course track, and it's mostly freeway riding.
I let it cool down and checked the catch can drain. Bone dry. Not a drop came out of the drain. The area around the K&N breather filter is completely dry and there is absolutely zero oil anywhere around the catch can. That tells me that the stock breather location in the airbox actually sets up this oil mess dilemma. There has to be a slight depression below ambient where the breather hose ties in, otherwise there wouldn't be any air traveling through the filter element. I'm thinkin that slight depression unbalances the vent system and results in oil carry-over. It must be worse with the stock paper element.
So far so good. I'm likin this contraption.
Armen, a shop vac on the breather? Man, you are ambitious.
Ya got any pics of your OoohBabyOoohBabyOooh Ducati reed assembly. That sounds exotic and expensive but I'm always up for another pony or two.