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

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)


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