It doesn't allow it and it is a one way valve. In only feel it pulsing out. Not sucking in.

Never noticed it but then my engine came with the better 86-90 engine breather design.

That is the purpose of a PCV.

I'm not getting the correlation or why you think my one way valve WOULD be sucking air.
I think the issue is you're getting air into the oil tank which I no longer am. I don't get 1 air bubble and oil is is returning faster. My tank level went up a little.
I put a piece of paper by the end of my krankvent. It's not sucking in.
Just started raining but tomorrow I'll see if I can take a video of it pulsing out.

You're killing me. :laugh:laugh:laugh:laugh

Just thinking out loud FourSpeed. :)

I didn't think you were sucking air to begin with.
I think I am.
Matter fact, I think all OEM 91-03s are due to that little hole in the pic above.
I am wondering about the design now.
I see that air/oil will separate upon impact of the umbrella.
I see some will get past the umbrella and settle in the little sunk in chamber.
04+ breathers also have that little holding space in the shelf between in/out hookups.
But they don't have any holes to drain the oil collected inside the breather unit.

Looking for more reasons why 91-03s don't have as many breather issues as later models.

Isn't there a tiny hole in the plastic housing on the later ones. Seems to me there is albeit tiny. Not sure if oil would drain out.

Perhaps the gases are being pushed past the guides into your combustion chamber when you get too much pressure?

I didn't see any holes in the 04 Up breather units in that area.
From the pics I've seen, it looks sealed past the umbrella to the vent port.
Can you look closely at your old ones to see if there is or isn't a drain there?

I have no issues at all (right now anyway) with engine breathing With head breathers.
This includes the dreaded CC pressure rising up and fighting drain oil in the pushrod tubes as is mentioned in the Deimus thread.
I flogged the Hell out of it a few days ago to try and make an issue.
I've no scavenging issues, no enhanced heat issues at sustained high RPM.
5500 in third on the highway, back and forth, stopped on side of the road checking for aeration...
The only cop I saw was near the house and he drove on as I quickly backed out of it. :hidechai
I have the OEM setup including the breathers into the A/C.
Only difference is a K&N in my ham can.

Mine are back in but I thought there was a pin hole on the bottom.
I could probably have solved my issue with the stock umbrellas too but I think this is better.
It's hard for me to judge how much of an improvement it is since my stock breathers were obviously bad. Just when they went bad is hard to say. Probably a progressive thing. I do know my motor runs better than I can remember. It sounds better and is less strained. I could tell this on first startup after using the krankvent off the breather hoses.
How much the pump helps is hard to say. I do know it felt better after the krankvent and before the pump but I think it's returning oil better with the pump.
Bottom line, imo, both were worthwhile and had positive results. How much is tough to say.

My thoughts exactly. If you're having breather problems, fix the breathers. If your bike is wet-sumping, install a better oil pump. If it's blowby, fix the rings. Each problem is easy to identify, and is repairable.