I thought twice about grinding my spacer all the down and only took a little of it off(half at most if that)allowing it to close a little sooner and create slightly more vacuum. It does close with the slightest amount of suction tho. With the better scavenging of the updated pump, it seems to be a good balance.
Also, with my bigger pistons, I assume I'm getting a bit more volume both ways.
There's absolutely 0 movement in the umbrella where it pushes in. In fact I had a hard time getting it out and back in and it's considerably sturdier.
I would think the flimsier umbrella and loose fit of the stock ones would leave room for too much variance as to when it closes. Especially if it starts warping from the heat like the plastic housings do.

You may be right about the combo you're using now.
Also, 91-03 models do not have the plastic housing, just the umbrellas.

It's the same umbrella that James sells for all 1991-1999, Evolution® & Sportster® models.
https://www.jamesgaskets.com/product/jgi-26856-89/

It also doesn't seem to be the umbrella that is the 'improvement'.
Same flimsy umbrella that I run.
The 'improvement' was machined ramps to and from the umbrella, the spacer and the shimming of the umbrella.

https://patentimages.storage.googlea...ngs-page-4.png

Sorry about the huge pic.
I linked it from the site.

None of this (to me) suggests removing or altering the spacer will harm anything.
(especially without testing to see what's happening there)
But it should be something to keep in the back of your mind in case problems do come up.

edit:
I say that mainly since I am not convinced of all the claims they have there.

I am also skeptical about some of the claims and struggle to see the 'novel aspect' beyond a better made umbrella
valve that you can site away from heat. Which is fine, if it works better than stock.

I don't know why the umbrella seems sturdier if it's the same one except maybe the heat has more of an effect on it.
I just question using the krankvent in conjunction with the stock ones because of the added restriction. But if it works for you Tomcat.
If i were to use it in the heads I'd like to remove the umbrellas but keep the housing. Not really possible tho.

I don't necessarily buy all the claims either but I do think it works better nonetheless.
I'd like to improve on the baffling in the cam chest tho it's Not that enough of an issue to make me go back to the heads where there's bound to be some oil anyway at higher rpm.

I am surprised Hayden offers no guidance about that. ET claimed their reed valve still worked with umbrella valves fitted in line
but their valve worked best on it's own.

As I suggested before, maybe all this needs is a pragmatic approach: if you get excess oil mist down your leg, gaskets that are oil misting
or notice that the oil tank is filled with foam, try renewing the stock umbrella valves (not easy on an the 86-90 engine due to availiability)
or replace them with a proprietary valve and see if it helps.

Regarding the oil baffle 60Gunner: Not sure if they would fit but the parts from the MK1 Evo breather oil baffle are: 26916-84 CAP, 26917-84 TUBE.

In practice I find very little oil comes out of the camchest breather, mostly water vapour. The stock 86-90 set up has an effective oil baffle and combined with a decent one way valve the oil mist should be minimal.

Well to be fair, I am going to move it to the heads for testing since I only ran it a couple miles that way.
But you're right. What does come out is pretty white and pretty runny. Not much oil content.
I'm not so sure keeping it in the motor is that good tho I'm sure it would evaporate.

Here is the 86-90 breather baffle tube Four Speed mentioned.
Gunner, since you're using steel, you may be able to fabricate a cage for the assembly.
The problem is gonna be that the OEM 'cage' for the assembly is molded into the cover, so there will be a gap there no matter what you do if not using sealant which I strongly advise against.

Mainly I say however, if what you have is working, then you've accomplished your goal.
But if you feel like modding, we'll be in waiting. :D

http://sportsterpedia.com/lib/exe/fe..._by_gary_e.jpg

http://sportsterpedia.com/lib/exe/fe...by_norsexl.jpg

http://sportsterpedia.com/lib/exe/fe...y_bryan350.jpg

:) Look at that fine engineering!