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-   -   Sportster Crankcase Pressure / Engine Breathing / Wetsumping and Mods (http://xlforum.net/forums/showthread.php?t=2073932)

dieselvette 31st July 2019 03:59

Quote:

Originally Posted by Hippysmack (Post 5766287)
as in the case of my RPM drop with the oil cap off.

I still think this is due to some other reason. Would you be able to repeat the test, but with the air cleaner removed? I wonder if you have some blowby that goes normally in the intake, but having removed the oil cap it doesn't.

With all the analysis of venting, I still go back to Aaron's test where "the motor was remarkably unresponsive to anything I did with the vent, except to remove it altogether" or something like that.

The oil drainback holes at umbrella valves exist pre-dating 2004 don't they? The oil drain hole is essentially a "leaky valve" which has no effect on performance.

Now, if your stock umbrellas are totally shot (60Gunner had this?) and you have no long hose attached, it's apparently not restricted enough especially on engines with 1200+ displacement, and air comes back in.

60Gunner did your failed setup have the stock breather bolts? or something with the same restrictive hole in it?

dieselvette 31st July 2019 04:09

Quote:

Originally Posted by Hippysmack (Post 5766574)
Which one closes faster:
A valve with more air behind it (I'm sure there is a scientific term for that affect) or one with less air behind it, given vacuum in front of either?

It's more a matter of which one lets *less air* back in while closing - one with less air behind it may close slower but the volume of backflow is still less.

One that has higher seat pressure will let less air back in - it is more "self-closing" and would also close faster in any scenario. That is probably the case with the Krankvent.

But more seat pressure also means it took more pressure to get it open in the first place. More enough to matter? Probably not, as things are not static.

Hippysmack 31st July 2019 04:13

Quote:

Originally Posted by dieselvette (Post 5766576)

Would you be able to repeat the test, but with the air cleaner removed? I wonder if you have some blowby that goes normally in the intake, but having removed the oil cap it doesn't.

I will try that.
When I checked head temps the other day, same thing happened then.
Just as a couple guys rode up to check on me for appearing broke down.
I'm sure it sounded like crap to them while stumbling with the cap off.

dieselvette 31st July 2019 04:19

Quote:

Originally Posted by Hippysmack (Post 5766574)
I'm not sure if it's an intentional leak.
That depends on how much oil actually does get past the umbrella during operation.
Oil is thicker than air and any oil to be drained from that tiny hole would be best done upon a vacuum in the crankcase.
So it might hold more oil than it actually drains until shutdown.

All good points. Oil that makes it past the umbrella, can be sucked back down. Adding to that idea - too much blowby could hinder this? CC would (on average) spend less time at vacuum? =more oil out the breathers?

Hippysmack 31st July 2019 04:26

Quote:

Originally Posted by dieselvette (Post 5766584)
Adding to that idea - too much blowby could hinder this? CC would (on average) spend less time at vacuum? =more oil out the breathers?

I don't know.
I'm going to make an attempt at a clear rocker box top.
May shed some light if I can keep it clean.

dieselvette 31st July 2019 04:58

Quote:

Originally Posted by Hippysmack (Post 5766586)
I don't know.
I'm going to make an attempt at a clear rocker box top.
May shed some light if I can keep it clean.

I have run many engines without valve covers (when making valve adjustments). It's surprisingly un-messy. But there is enough oil flying around, that a clear valve cover would definitely NOT stay clear.

dieselvette 31st July 2019 05:02

There are a few facts still on the table, but I think I dare to summarize anyway:

CC pressure: The function of the umbrella valves isn't that picky. They just need to stop a big gulp of air from coming back in. They don't even need to seal 100% It's less picky if you have small breather holes in the bolts, like a stock '04 bike. If you have aftermarket banjo bolts, you may need to add restriction, depending on their design. Or, add external umbrella valve.
IF the umbrellas are stiff/old, this may cause slower action in both directions and could be enough to cause a problem, especially if stuck open. Replace with new, stock ones, or re-vamp in other ways if you prefer (cam chest vent, etc.) But then you need an oil catch can which isn't otherwise required for 04-up bikes (see below).

Where to vent: It's worth the effort of re-directing your breathers outside the A/C. More hp short-term, cleaner combustion chambers long-term. If you need a catch-can, use one. If you want to keep bugs from living in there during storage, add a filter.

Find air leaks: If you have an air leak, it will most likely present as an oil leak. Inspect everywhere, including outside of tank for traces of oil anywhere. Fix all oil leaks. Air leaks comprimise the breather dynamics.

Oil out breathers: The '04-up umbrella valve assy, with its oil-catch labyrinth, works great assuming you don't have too much blowby. Another cause could be too much air going IN somewhere, somehow - see above.
(All the 04-up bikes I've seen with stock breather setup, vented outside, have NO oil come out as long as the engine is in good shape - Hippy can you think of any oil-pukers that for really really really sure were in perfect running order?)

Wet-sumping: If your breathing system isn't optimized, do that first. If you have an 04-06 or any performance mods, update the oil pump to '07+. It's not cheap, but not expensive either. Alternative is to ride differently. If the oil pump doesn't fix it, then....?

Hippysmack 31st July 2019 05:09

Even though I only do engine work now when one breaks, I still have a tall set of the chrome ones with the top cut out of them.
Really cuts down on oil splash.
I've only had a few that didn't spill oil. But splash (to some extent) with most.
It's not a lot of spillage, but I tend to double check or more on valve lash and usually get splash.

But that's a different animal.. maybe.
I have the thick plexiglass and I plan on using "Right stuff" to put it together with sides.
I haven't put my hands into it yet but my brains all in.
I was thinking Rain X on the inside.
Then I thought of the official name??? film that goes inside the helmet shield to stop fog but that's probably a stretch.

dieselvette 31st July 2019 05:20

Quote:

Originally Posted by Hippysmack (Post 5766550)

A theory was made that the inertia will keep the oil in position in a motorcycle during cornering.

But with the oil tank being separate in a dry sump, the small sump area doesn't allow much variance to sway I'd think.

When I have a regular coffee cup in the cupholder behind the windshield, there is NO left-right slosh. But the fore-aft slosh can half-empty the cup through the 1/4" drinking hole by the time I'm up to speed. So I turn it facing sideways, and that works much better.

Under hard acceleration, it is conceivable that oil is sitting against the rear of the crankcase and not being scavenged at all. Upon deceleration this should be picked up quickly and/or slosh to the front. But at some point there's enough oil to keep the scavenge inlet covered, and at high RPM this would empty quickly - but at lower RPM, not as fast.

Hippysmack 31st July 2019 05:22

Quote:

Originally Posted by dieselvette (Post 5766596)

Hippy can you think of any oil-pukers that for really really really sure were in perfect running order?


All engines no matter what year are subject to this.
78< models had the timed breather.
If the timing is wrong on it, it'll puke.
79-up models all were a little different but the same as well.
Rubbermounts, by XLF poll, don't seem to be as bad until the engine is upgraded.
That seems to be the game changer.
All in different phases of health I'd imagine though.

Hippysmack 31st July 2019 05:35

Quote:

Originally Posted by dieselvette (Post 5766600)
Under hard acceleration, it is conceivable that oil is sitting against the rear of the crankcase and not being scavenged at all. Upon deceleration this should be picked up quickly and/or slosh to the front. .

Scavenge port is in the rear.
I agree but wouldn't that be in reverse?

Quote:

Originally Posted by dieselvette (Post 5766600)
But at some point there's enough oil to keep the scavenge inlet covered, and at high RPM this would empty quickly - but at lower RPM, not as fast.

The scavenge is bigger than the feed side.
You will always have a spurt / no spurt condition from the return line in the oil tank.
Check it out next time you can.
There should be moments I'd suppose when it's pulling straight oil though.
High RPM is where you want the oil to return faster but inherent conditions hinder that.
In theory, feed / return ratio should be the same at idle as in high RPM.
It's other conditions that change that.
It's not the speed of the oil pump that "can't keep up".
It's other conditions hindering the pump.

Hippysmack 31st July 2019 05:49

Thinking out loud and may be full of it.
Mine lopes like Hell on startup.
Oil is thicker, no oil in the cup to drain from that little hole and air is pulled thru it.
Bunny says you get no measureable (extra) blowby on startup.
But that pesky hole...
Progressively, as oil heats up, it fills the cup, no air pulling in the hole.
Idle levels.
Just like when the oil cap goes back on.

I can't believe there is only a few of us seeing this with the cap off.

harley506d 31st July 2019 10:42

Well, just for peace of mind i just had to re-check my breathers were working.
Not as easy as you would think though.
The best way i found was to block with my thumbs over both ( and after a few seconds the motor lets you know it's not happy) and release each one individually. Both fine.
Also checked to see if there was any difference to RPM when the oil cap was loosened, no change.

dieselvette 31st July 2019 14:45

Quote:

Originally Posted by Hippysmack (Post 5766605)
Scavenge port is in the rear.
I agree but wouldn't that be in reverse?

Fair enough then, oil slosh is not a factor worth considering.

bustert 31st July 2019 14:56

hummmm?????
think "U_TUBE" effect
really not a vacuum but diff'l

Hippysmack 31st July 2019 15:13

Quote:

Originally Posted by dieselvette (Post 5766661)
Fair enough then, oil slosh is not a factor worth considering.

Actually it is worth considering.
Think steep hills, on the way up and down.
Seems on the way down depend more on positive CC pressure.

Hippysmack 31st July 2019 15:16

Quote:

Originally Posted by bustert (Post 5766665)
hummmm?????
think "U_TUBE" effect
really not a vacuum but diff'l

There is a difference of course.
You mean on upstroke?

Hippysmack 31st July 2019 15:18

More food for thought.

Some potential air leak areas are in the pic below.
If these areas allow air to be pulled in the engine on upstroke, the added air will compound any other existing breathing problems.

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

60Gunner 31st July 2019 15:22

Maybe fine but could be better is my position.
As to venting out the cam chest needing a catch can, I'm not using one. Filter either.
I was using aftermarket breather bolts.
I think the question of the krankvent being an improvement would be best answered by someone with supposedly fine stock breathers trying it.
Didn't Tomcat already do this? Seems to me his were fine and went to the krankvent anyway and noted an improvement.

60Gunner 31st July 2019 16:27

I could move mine back to the heads. I don't think the location makes much difference. I can't test with or without the krankvent as my stock umbrellas are shot and I'm not replacing them when the krankvent clearly says it works best without them in the picture anyway and should be removed if using the krankvent there.
If I notice less dripping, I may leave it there. But if it drips any from there, I'm going back to the cam chest just for cosmetic benefit of no hoses dangling from the heads. I never could stand that mess or having to pull it and loosen the breather bolt just to adjust my carb.

60Gunner 31st July 2019 19:46

Quote:

Originally Posted by Tomcatt (Post 5766719)
KranKvent connected or not connected I can't tell a difference. I was listening and watching rpm, IAC steps and MAP and didn't see a change except the usual decrease in IAC steps as it idled and that didn't seem to be affected by the KrankVent being connected or not.

There was a bit of oil in the KrankVent housing. In the outlet section after the umbrella. In terms of volume maybe 5 or 6 drops.

While idling you can barely see the KrankVent umbrella moving. It doesn't "flap", you can see it just barely not staying seated. It looked the same idling or if I held ~3,000 rpm.

Can't help but wonder how this is affected by leaving the stock breathers in.

60Gunner 31st July 2019 21:06

But I can't vent thru the stock head breathers that aren't functioning. We already know unrestricted air in and out is bad.
I'm wondering if you could tell a difference between working stock breathers and the krankvent without the stock breathers in the picture.

Four Speed 31st July 2019 22:14

Quote:

Can't help but wonder how this is affected by leaving the stock breathers in.
Are Hayden not clear about this?

60Gunner 31st July 2019 22:58

Quote:

Originally Posted by Tomcatt (Post 5766780)
Can't because my OE breathers are still in place.

"We already know unrestricted air in and out is bad." But can you actually tell a difference with your KrankVent in place vs the hose open? Easy enough to try.

Pretty much what I did when I ran with nothing but the big breather bolts and umbrellas that let air in as fast as out.
Besides, it was already tried years ago running open breather with no one way valve. Pukes a lot of oil and outgoing can't keep up with incoming and pressure under the pistons results.
A reversed one way in the heads was also tried. Air in the heads and out the cam chest. Foaming oil galore.

Air in = bad.

Tomcatt 31st July 2019 23:53

Quote:

Originally Posted by Four Speed (Post 5766795)
Are Hayden not clear about this?

I guess I'm just skeptical. There's too much internet expertise that turns out to be wrong.
It's known that taking off your oil cap makes your bike idle like crap, if it will idle, but when I remove mine nothing changes... an easy example of why I'm skeptical about a lot of this "long known" stuff.

Too many assumptions, too little real verification.

60Gunner 1st August 2019 00:41

Quote:

Originally Posted by Tomcatt (Post 5766840)
I guess I'm just skeptical. There's too much internet expertise that turns out to be wrong.
It's known that taking off your oil cap makes your bike idle like crap, if it will idle, but when I remove mine nothing changes... an easy example of why I'm skeptical about a lot of this "long known" stuff.

Too many assumptions, too little real verification.

Well if it was ok to just breath in and out, they wouldn't have put the umbrellas in that they did.
A lot of different stuff was tried in one thread here spanning quite awhile and 130 pages. Results were posted. I guess either you chose to give certain people's past experiences merit and go with it or you don't. No one that has done the krankvent or cam chest for that matter have ever gone back. Not that I'm aware of anyway. Some of them are still here. Some of them were just as skeptical til they tried it.
Why did you put a krankvent on if your breathers we're working fine? Mine obviously weren't and that's why I started looking into alternatives other than just replacing a setup I didn't much care for when it was working.

dieselvette 1st August 2019 02:45

Quote:

Originally Posted by 60Gunner (Post 5766852)
No one that has done the krankvent or cam chest for that matter have ever gone back. Not that I'm aware of anyway. Some of them are still here. Some of them were just as skeptical til they tried it.

I really, really like your setup with the krankvent out the cam chest. For the fact that it works well, and gets the paraphernalia down and out of the way.

But I feel like it's a compromise, because you will have occasional oil release from your bike. No matter how small, to me that's significant because I tend to put a lot of miles on in a day/week and ive seen on buells what a mess it can make on those kinds of rides if you don't have a catchcan.

My stock setup never had oil come out the breathers, or anywhere else except that stupid ebay oil cap. Even though the rings were shot, nary a trace of oil in the a/c.

Now, maybe I got lucky and somehow had a vacuum on the CC, and that's how I got away with it, I may never know.

But with this rebuild im going to start with stock, new umbrella valves and give it a chance to work, having a little more compression and cams and RPM. If that works I may entertain the idea of putting the old ones back in, just to prove that out (stiffness of the rubber). If it doesn't work then i'll have to go to the krankvent and would probably leave in the stock umbrellas to catch oil, if they can.

Hippysmack 1st August 2019 06:30

Quote:

Originally Posted by Tomcatt (Post 5766840)
I guess I'm just skeptical.
Too many assumptions, too little real verification.

Skeptical is a good thing.
That's how other ideas are formed.

When head breathing, leaving the OEM breathers in place with external PCV should add more restriction whether the umbrellas are good or bad, still more restriction.
If you pulled your krankvent, with the OEM umbrellas still in place, and nothing happened,
Then your OEM breathing system is still working...at idle anyway.
Adding the krankvent inline from there does add restriction just like the smaller breather bolt does.
To what extent of change? :dunno
From discussion here, it raises CC positive pressure, better scavenging, splash lube.
And the krankvent seals well enough to not allow it to get out of control from 'differential' when the pressure is reversed?
just thinking out loud.

Leaving the umbrellas in while externally breathing does need to be tested with a flow meter as Four Speed mentioned to see what is actually happening.
That way it's not a guess or 'works for me' piece of data.

Hayden or any other company is not going to tell you to put theirs inline with the OEM breathers.
In case something went wrong, they could get sued.....

60Gunner 1st August 2019 12:56

Quote:

Originally Posted by dieselvette (Post 5766866)
I really, really like your setup with the krankvent out the cam chest. For the fact that it works well, and gets the paraphernalia down and out of the way.

But I feel like it's a compromise, because you will have occasional oil release from your bike. No matter how small, to me that's significant because I tend to put a lot of miles on in a day/week and ive seen on buells what a mess it can make on those kinds of rides if you don't have a catchcan.

My stock setup never had oil come out the breathers, or anywhere else except that stupid ebay oil cap. Even though the rings were shot, nary a trace of oil in the a/c.

Now, maybe I got lucky and somehow had a vacuum on the CC, and that's how I got away with it, I may never know.

But with this rebuild im going to start with stock, new umbrella valves and give it a chance to work, having a little more compression and cams and RPM. If that works I may entertain the idea of putting the old ones back in, just to prove that out (stiffness of the rubber). If it doesn't work then i'll have to go to the krankvent and would probably leave in the stock umbrellas to catch oil, if they can.



You're not running a vacuum with breathers that allow air back in and restrict it going out. Most oil mist will get sucked into the intake. If your rings are shot that excessive blowby is going somewhere.
Probably have leaky valve guide seals too allowing the the crankcase pressure to push blowby past and into the combustion chamber if those are stock. A known issue if yours were never replaced. Something I also replaced when I did this build because mine were leaking.
Your poor ring seal would also lend to crankcase pressure not vacuum.

Hippysmack 1st August 2019 15:08

Well Hell,

I finally made it thru the "Background" part of the Hayden patent, Four Speed.
https://patents.google.com/patent/US5881686A/en

Some of the information in the patent material seems to confirm what we've already disccused in this thread.
Either that or they just BS as well as we do.


A crankcase breather valve for ventilation and pressure control within the crankcase of an internal combustion engine in which pistons stroke upwardly and downwardly in a synchronous movement. The valve is inserted into a breather hose which conducts gases into and out of the crankcase. The valve comprises a resilient valve member, preferably an elastomeric umbrella-type seal, spaced above a seal seat and forming a gap there between through which gases may flow either direction during portions of the pistons' stroke cycle. The valve construction permits three operating modes: firstly to permit the egress of positive pressure gas out of the crankcase and through the gap while the pistons stroke downwardly; secondly, to permit the ingress of a small amount of gas back through the gap into the crankcase when the crankcase pressure changes from positive to negative; and thirdly to check further ingress of gas into the crankcase at greater crankcase suctions, developed when the piston's are moving upwardly.

The breather valve has 3 functions.
1. To allow positive gasses to leave the engine.
2. To allow a small amount of atmosphere back in.
3. To regulate how much atmosphere gets back in.


On Harley engines produced earlier than 1993, the management of crankcase pressure is performed with a breather gear, driven and timed by the crankshaft. The gear is typically set to open and vent crankcase gases between 10° before top dead center (before TDC) through 75° after bottom dead center (after BDC). The breather gear vents crankcase gas to a separate camshaft chamber where the bulk of the oil mist is knocked out. The de-misted gas is then directed through a breather hose to the air cleaner. Due to the inherent physical limitations, the gear timing venting is not optimal at all engine speeds and throttle conditions. High crankcase pressures still result.

In another aspect, the oil system of Harley engines is also rather unique, being of the dry sump variety and having a separate oil tank. A scavenging pump collects oil from the bottom of the crankcase, routes it through an oil filter and on to an oil reservoir or tank. Oil flows under gravity feed from the oil tank to a feed pump which delivers oil to the engine components. Baffles in the camshaft chamber separate returning oil mist from crankcase gases before the oil collects at the scavenging pump. There are two aspects of this system which are sensitive to crankcase pressure. Firstly, excessive suction in the oil tank, the head space of which is in communication with the crankcase, adversely affects the supply of oil to the feed pump. Secondly, lack of a head of oil at the inlet of the scavenging pump and excessive suction in the crankcase can starve the scavenging pump of oil. In short, the excessive suction can result in oil-related engine failure.

In post-1993 Harley engines the breather hose has been relocated, from the crankcase, to each of the two rocker housings. Crankcase gases and pressure communicate with the rocker housings through the push rod tubes. A one-way check valve mounted within each rocker housing releases excessive crankcase pressure into the housing. The check valve is an "umbrella-type" valve having a port or ports blocked with an elastomeric umbrella valve head. The umbrella is normally closed over the port to prevent inflow of gases into the crankcase. Pressure flexes the umbrella off of the port so as to release gases from the engine. A small bleed hole is provided which permits collected oil to drain back to the crankcase. It is apparent that the bleed hole can also permit some gases to return to the crankcase. In the stock arrangement, a port directs the gases directly into the air cleaner. As an accessory, after-market cross-over tubing can be installed between the two rocker housings. A "tee" in the tubing directs the crankcase gases to a discharge tube and filter which removes oil mist.

Others have utilized crankcase breather valves in the context of conventional 4-stroke engines. The valves are known for reducing oil seal leakage by releasing excess pressure and forming a predominately negative pressure in the crankcase. Several breather valves use the "umbrella-type" valve heads ("umbrella"). For instance, in U.S. Pat. No. 5,067,449 to Bonde and U.S. Pat. No. 5,205,243 to Buchholz, disclose crankcase breather assemblies. An assembly is inserted into a port formed in the crankcase. The assembly incorporates an outer groove which retainably engages a lip formed in the port. The assembly further incorporates an umbrella which covers and seats over a circular array of ports. The umbrella is normally-closed so as to ensure only one-way flow through the ports. In U.S. Pat. No. 5,027,784, Osawa et al. improved the operability of an umbrella-type valve by interposing a washer between the umbrella and the ports. The washer reduces over-flexing and premature failure of the umbrella. Despite the presence of the washer, Osawa's umbrella still rests in the normally-closed position.

Thus check valves of the umbrella-type are known and they are all of the normally-closed, one-way variety. Accordingly, while these valves permit flow out of the crankcase on over-pressure, they do not permit any gas flow back into the crankcase, except for a small amount of sealing hysterisis.

While the synchronous piston movement in a Harley Davidson engine can benefit from a reduction of maximum crankcase pressure, it must do so while avoiding the creation of excessive crankcase suction which can be associated with loss of oil pump operation. Further, a device which meets the above objectives must do so without modification to the crankcase.


The gear driven breather's last year was 1978.
Shouldn't somebody trying to design a better Harley part know that?
They completely left out the 79 style internal reed valve.
They are representing ironhead technology up to 1992.
They also cite excessive suction in the oil tank and lack of an oil head at the scavenge port in the sump as being sensitive to crankcase pressure.

1. The head space in the tank (of which is in communication with the crankcase) adversely affects the supply of oil to the feed pump.
How????
Pressurized air above pushes down on the oil below it which is being sucked out from below.
Vacuum in the air above is pulled from above, not below and the oil in the tank is much heavier than the air above.
There is no way I can be convinced that CC pressure sucks oil from the tank unless it's already been comprimised (badly) by other means.
2. They are saying too much vacuum (negative pressure) can cavitate the oil pump.

It also says the OEM umbrella is normally closed... (but they don't say sealed).
And as we know, they DO let air back into the crankcase.

So there you have it.
The drain hole we have been discussing has a dual purpose.
1. It drains oil that gets past the umbrella.
2. It helps to keep vacuum pressure from rising too high to keep from busting seals.
edit:
That may explain the size of the hole as well.


SUMMARY OF THE INVENTION
It has been determined that the pressure-related problems of the simultaneous upward and downward action of the pistons includes not only affects seal-leakage but also impacts on engine power. Further, direct application of conventional one-way flow check valves for releasing crankcase pressure results in undesirable side-effects, namely a loss of power at higher engine speeds and the formation of excessively high crankcase suction. Further, an external in-line device is preferred to avoid modifications to the engine crankcase.

More particularly, a device is provided which is inserted into the existing external breather hose. The device permits a small amount of gas flow back into the crankcase as the pressure in the crankcase begins to be drawn negative, thereby ultimately avoiding excessively high crankcase suction at the top of the pistons' stroke.

Thus, in a broad aspect of the invention a novel valve is provided for installation on an engine, such as a Harley Davidson motorcycle engine, which has two or more pistons which move simultaneously upwardly and simultaneously downwardly. The valve is installed on a breather hose extending from a port on the crankcase for discharge outside the crankcase. The valve is constructed such that it operates to control the flow of crankcase gases in three modes. Firstly, to permit the egress of positive pressure gas from the crankcase while the pistons are moving downwardly; secondly, to permit the ingress of a small amount of gas back into the crankcase when the crankcase pressure changes from positive to negative; and finally to check the further ingress of gas into the crankcase at greater crankcase suctions when the piston's are moving upwardly.------

Preferably, the valve comprises the following construction for implementing the three operating modes. Firstly, the valve comprises an inlet, and outlet and a valve chamber intermediate the inlet and outlet. Within the valve chamber, a valve seat is formed at the discharge of the inlet to the chamber. A resilient member is spaced above the seal seat so as to form a gap through which gases may flow either direction. Accordingly, gas is able to flow from the inlet, past the member and on out of the valve's outlet. Under low pressure differentials across the member, gas will also flow back from the outlet, past the member, through the gap and out of the inlet so as to return to the crankcase. Under higher pressure differentials, the member flexes and blocks the seal seat, preventing further back flow from the outlet to the inlet and allowing the crankcase pressure to become negative.

More preferably, the resilient member is an elastomeric umbrella-type valve head, or a flexible reed.


It says the OEM umbrellas result in undesirable side-effects, namely a loss of power at higher engine speeds and the formation of excessively high crankcase suction. Further, an external in-line device is preferred to avoid modifications to the engine crankcase.
(They can't make money by redesigning our engines)

But if they increase suction, why does it detail that the (OEM) drain hole actually keeps high vacuum from forming?

Their "novel" breather is being made for engines "such as a Harley Davidson motorcycle engine".

Their primary arguments is their new valve is external, increases HP "slightly" and keeps down excess vacuum BECAUSE of the contolled intake of atmosphere before it closes.
They say their new valve also let's a small amount of back pressure to come into the engine "ultimately avoiding excessively high crankcase suction at the top of the pistons' stroke".
(which is the same thing OEM umbrellas do)
Regardless of what anybody says, the OEM umbrellas do work as designed.
The argument against them is their location and the fact that they are under heat there and get hard faster (shorter maintenance intervals).
The krankvent is also under heat as it sits inline from hot CC pressure coming out of the engine.

The major function of the krankvent is to allow air to pass back and forth from inlet to outlet during low pressure differentials.
But on high differentials, the umbrella closes down on suction.

So, according to the patent material, removing or altering the 'spacer' adds higher vacuum upon end of upstroke.


edit:
The drawing description says "The 'nitrile' umbrella is available from James Gaskets of Medesto, Cailf., Part No. 26856-89".

The OEM umbrella has a slight up and down play.
The Hayden assembly shims the James umbrella to prevent that movement and to adjust the air gap around it.

Various modifications are apparent to those skilled in the art. For instance, variances in the materials of manufacture of the valve head will clearly affect the gap used. Further, use of a reed-type valve, spaced above a seal seat and being enclosed within a housing, can be seen to provide an equivalent valve in these instances.

edit:
I'm curious what gas / gas by-product does to nitrile.
I know raw gas melts my nitrile Harbor Freight gloves (albeit 5 mil)

60Gunner 1st August 2019 16:37

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.

Hippysmack 1st August 2019 17:04

Quote:

Originally Posted by 60Gunner (Post 5766960)
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.

Hippysmack 1st August 2019 17:28

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.

Four Speed 1st August 2019 19:02

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.

60Gunner 1st August 2019 19:05

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.

Four Speed 1st August 2019 19:11

Quote:

I just question using the krankvent in conjunction with the stock ones because of the added restriction.
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.

Four Speed 1st August 2019 19:24

Quote:

But I feel like it's a compromise, because you will have occasional oil release from your bike.
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.

60Gunner 1st August 2019 20:42

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.

Hippysmack 1st August 2019 21:35

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

Four Speed 1st August 2019 21:58

:) Look at that fine engineering!


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