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  #351  
Old 30th July 2019
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Yeah I read that. Seems its expired.
My take on the ring allowing a small amount back in is as much vacuum that will still allow good scavenging. The more vacuum the better. I ground that ring down somewhat allowing little to no air back in increasing vacuum. Probably not by much but...

I did a compression test and while it is slightly higher, 5lbs, the video in the link below shows why it cannot be trusted to give a proper reading. Hammer Dan told me the same thing. Everyone they've tested was off by by roughly 20lbs light. This guy suggests it's more and another guy actually tested it on a small engine. It came up with under 30lbs while a known good gauge was at 60lbs.
So while it's slightly higher, I think it's even more.

https://youtu.be/q1H7550B48I

Here's another review.

https://youtu.be/4ke8t5L1EPg

Last edited by 60Gunner; 30th July 2019 at 21:33..
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  #352  
Old 30th July 2019
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"The connector to the boots special or can I get it anywhere?"


I bought all the bits off ebay. If i remember rightly, it was all 8mm. 2 straights and 1 "T".
Caps were for some old Brit car, but any with soft rubber should be fine.
The innards obviously removed and the part that fits over the plug cut down some. "O" ring on breather bolt removed.Cut the air filter sleeves that normally slide onto the breather bolts to leave about a 1/8" stub, and that should seal against the plug cap rubber when filter is tightened down.
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  #353  
Old 30th July 2019
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Quote:
Originally Posted by 60Gunner View Post
I'm going to check the better ring seal thing with a compression test later after I ride. If it's noticeably better, even 5lbs. higher, that's a good indication of better ring seal.
That's an really good idea.

If you dare, you could do this test with vs without the Krankvent installed.
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  #354  
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I have a theory about the "purposely leaky" check valves (stock has the "oil drain hole" , krankvent has the "ring" that can be modded) --- this could be simply a liability/safety concern.

While parked, there is the potential for pressure/vacuum buildup in the cc. With the crankcakse totally sealed, and potential for unburnt fuel vapors to exist in the CC (ever drained the oil on a car that wouldn't start, and found it full of gas?). Or, consider if there is fuel above the rings that could be drawn down if the cc is at vacuum.

The intentional "leak" at the check valve(s) allows the cc to stay equal to atmosphere when the engine isn't running. In stock, working form it apparently has little/no effect on the operation while running, and prevents oil from coming out.

Krankvent designers apparently believe the intentional leak has little effect, too, and if connected at the heads while leaving the stock umbrella assy in place, you would also retain the oil catching feature.

Or, maybe it's not a safety issue but a different reason.
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  #355  
Old 30th July 2019
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Originally Posted by dieselvette View Post
I have a theory about the "purposely leaky" check valves (stock has the "oil drain hole" , krankvent has the "ring" that can be modded) --- this could be simply a liability/safety concern.
Or it made a generic "umbrella" patent-able because it was then not just a generic umbrella.
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  #356  
Old 30th July 2019
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I'm with Tomcatt on this. Umbrella valves typically relax when there is no flow and deform in the direction of pulses when there is.
A reed valve may be slightly different as most are held shut until the reed flexes due to an air pulse.
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  #357  
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Quote:
I did a compression test and while it is slightly higher, 5lbs
Interesting find 60Gunner!

Yes, some gauges are garbage. Mine has a valve in the adapter head which is good, but it is 14mm,
so I have to add a reducing adapter which adds volume; not so good. But even if your gauge is out,
you are using the same gauge, so if there is a measurable difference, it should be reproducible with
a more accurate gauge. You could take the average of three tests to see what the test-retest variability
is and then do the same without the Krank vent.
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  #358  
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It goes as far up as it going to on the 1 stroke and that's it. Checked the one for loan at O'Reillys. Same thing. I'd like to know what my compression actually is but I don't want to spend the money on a good tester to use once.
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  #359  
Old 31st July 2019
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I agree the balloon is not an accurate test. But there is merit to the reaction of the balloon.
Heating thin rubber with hot (compress-able) air and asking it to be consistent is not very scientific.
But that is the premise that DK Custom is using to sell their product.
It would be better for them to include the non-scientific nature of the testing so as to not make us feel cheated with the results.
I haven't received anything from the request that I posted on their thread that mentioned the info for the balloon testing.
No offense guys, but this is the part about cracking a few eggs I mentioned earlier.....

I made some notes from the Engine Labs article.
While informative, I'm still working on the angle all this bears on a Sportster engine.
In all due respect, it made me even more against adding a vacuum pump in a Sportster engine.
It is also written by instrument to sell products to you.
But let's break down some of the information that relates.


PCV Valve

All internal combustion engines generate some type of crankcase pressure in the form of blow-by.
Blow-by is combustion gasses that escape past the piston rings.
In the early 1960s, General Motors identified crankcase gasses as a source of hydrocarbon emissions.
They developed the PCV valve in an effort to help curb these emissions.
This was the first real emissions control device placed on a vehicle.
While most of us who are performance enthusiasts will roll our eyes when emissions controls are even mentioned,
GM actually did the performance world a favor here.
Not only does a properly operating PCV system reduce the overall emissions output of a vehicle while at the same time not sacrificing horsepower,
It also has other benefits. It improves gasket seal, and prolongs gasket life by reducing the blow-by effect.
Further, it also helps reduce the amount of oil an engine consumes through the combustion cycle, or loses due to leaking seals.


The PCV in our engines has a bigger role than emissions.
The engines are designed to incorporate a PCV.
So a PCV valve in our engines can be viewed the same as a piston or a carburetor.
The engine was designed with it being an integral part of the system.
An umbrella valve is a form of PCV just as the krankvent with or without a reed valve (which is another form of PCV).


Oil Separator (Catch Can)

Not long ago Moroso released a video of one of their air-oil separator systems in action.
The separator was placed in-line with the PCV system on a stock Cadillac CTS-V.
The car had only 24,000 miles on it, and the test drive lasted about thirty minutes.
They included both hard acceleration, and just general cruising like the car would likely see in regular use.
You can see several puffs of oil and water vapor enter the clear container that was substituted in place of the aluminum one for this video.
This is further evidence that the factory PCV system on a high-performance, unmodified engine, with low mileage is inadequate.
The car’s owner states that after about a week of regular driving there’s typically about 3/4" of oil in the separator.
While this may not sound like a lot, consider how much oil that is over the course of an oil change interval, a period of twelve to sixteen weeks on average.
So every twelve weeks the separator would accumulate about eight inches of oil in its reservoir.
The actual volume would vary based on the dimensions of the separator, but that is definitely a substantial amount of engine oil.
Moroso’s Air-Oil Separators plumb directly into the car’s PCV system.
Using mesh filter media, they capture the majority of the engine oil that escapes the crankcase and is normally sent back to the engine through the intake.
“Removing this oil mist before it re-enters the engine reduces detonation, and deposits on the intake track, including the valves themselves,”
Most of the separators have a total volume of just under a quart of oil and have a drain valve to allow the collected oil to be cleanly and easily drained into another container.
Moroso offers these separators in both a universal style and direct fit for multiple vehicle specific applications.
They also offer Air-Oil separators for dry sump and racing applications.
These separators work much the same way that their street systems do, however they are designed for car’s running at the track rather than cars that are street driven on a regular basis. These systems do not plumb into the factory PCV system, instead they are stand alone separators.


Catch cans are in use on Sportsters all over.
I, for one, am concerned of the back pressure from long oil lines, routing and fittings past the breather valve.
Anyone that is trying to lower CC pressure could in fact raise it instead with a bunch of restrictions in the vent path.
So you are not always helping with the intended course of action.
Sometimes these things may hinder more than help.
Again, there needs to be testing involved.


Wet Sumping

In a wet sump system, high Gs in racing / cornering can cause oil to move away from from the pump inlet.
In a dry sump system, the oil still returns to the pan just like a traditional wet sump system.
However, it’s immediately pulled away by the scavenge stage of the external oil pump.
With a dry sump, the migration of oil in the pan under high-g loads is negated since the oil is collected almost as soon as it returns to the pan.
This rapid collection also helps to ensure that the pickup is not starved for oil under such conditions that would cause the engine to suffer a drop in pressure or total lack of lubrication.


I've also read on the forum where that was discussed.
A theory was made that the inertia will keep the oil in position in a motorcycle during cornering.
I haven't enough info to weigh in on that.
In a wet sump engine, the oil in the pan can sway, I agree.
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.
And positive pressure is still directiing the flow direction.
But under the right conditions, who knows?

In our engines, oil is not immediately pulled away by the scavenge pump.
The oil in the sump has to travel up hill mainly by suction to get to the pump where the gerotors force oil back to the tank.
There is a suction created by hydraulic seal. Check.
But the oil flow to the return gerotors is dependant on how much suction the pump can muster from the scavenge port.
Positive pressure is suppose to keep oil to the scavenge port.

-----------

Vacuum

Sometime in the late 1970s to early 1980s professional engine builders discovered that applying vacuum to the crankcase would in-fact improve engine performance.
Wade Moon, from Peterson Fluid Systems, tells us, “Twelve to fourteen inches of vacuum is a pretty safe area to be at.”
Vacuum applied at around twelve to fourteen inches of mercury (HG) will improve ring seal, allowing lower tension rings to be utilized.

This also improves oil scavenging, cavitation, and windage, getting oil away from moving parts and back to the pickup faster.
Moon went on to tell us “We have had customers tell us they have seen a 35 hp increase pulling fourteen inches of vacuum.”
This makes running a vacuum pump on a racing engine that much more appealing.

Moon also pointed out two other key areas to keep in mind when selecting a vacuum pump.
Block material is one; an aluminum block can be harder to pull vacuum in.
At higher RPM the cylinder walls actually move a little, breaking ring seal which has an impact on overall vacuum.
Fuel type is the other area to consider; gasoline or methanol.
Methanol powered engines typically have greater blow-by, requiring a larger pump to generate and maintain proper vacuum.

Above 14-15 inches of vacuum, you pull too much oil away from the wristpins and cylinder walls,” said Meier.
In these cases, the higher end engines will employ measures such as oil squirters to spray the wrist pins, as well as special camshaft squirters, and even other provisions to oil the rocker arms and valvetrain.
All of this must be taken into account when running higher levels of vacuum.


They are discussing applying vacuum to a V-8 engine giving 12-14 inches of mercury (HG).
How much vacuum is better or too much for a Sportster 45 V-2 engine?


Dry Sumps and Vacuum

With dry sump systems vacuum is applied to the crankcase whenever a scavenge stage is not drawing oil from the system.
This means that there is not usually a need for a separate vacuum pump in a dry sump system.
“All dry sump pump scavenge stages will move oil and air.
Not all scavenge stages are pumping oil all the time, so if there is no oil then they move air,” says Moon.
How much vacuum is determined by the pulley selection,
design of the pump,
number of stages,
and the amount of time each stage spends scavenging oil compared to the time it spends creating vacuum.
This means that in a dry sump setup, vacuum must be monitored appropriately to ensure that it’s being applied properly throughout the engine’s operating range.


The first line doesn't seem to apply to a Harley.
This part suggests vacuum helps scavenging.
I'd have to have a complete understanding of a dry sump auto system before commenting on the advantages in that in an auto.

But this is not what Harley Davidson Motor Company says about their engines.
Two different systems.
Air vacuum being pulled up on upstroke pulls oil away from the scavenge port.
We use scavenging and POSITIVE air pressure to return oil.
The FSM specifically says "On piston downstroke" which is not a vacuum condition.
Vacuum is applied on upstroke but the gerotors are trying to scavenge during all strokes.

Now I can see the pump continually trying to scavenge.
On downstroke, there is oil at the inlet to be scavenged.
On upstroke, the oil is pulled away from the inlet but the same time the pump is sucking out what's in the passage.
Then downstroke gives oil back to the passage.
The pump still has hydraulic seal as the expended oil still leaves a film inside the pump cavity.
And that is helped also on 98-up engines with the cam chest port.
It still receives oil even on upstroke to help keep the hydraulic seal in place.

I agree as we have discussed before, the pump will move oil and air.
Not all scavenge stages are pumping oil all the time, so if there is no oil then they move air. ??????
We're not using different scavenging stages.
It's just one set of gerotors with either one or two inlets depending on year model.
They seem to be talking multi-stage oil pumps which we don't have.

This suggests that our oil pumps are actually creating air vacuum.
Wouldn't that also need a separate system to pump into than back to the cam chest positive pressure to actually create a vacuum from the pump?
(as in removing the vent line from the oil tank?).
The positive displacement pump requires a hydraulic seal to create suction at all which means it can't suck air at the same force as oil.
It can move air but not with force as it does the oil.

Vacuum pumps are spec'd for automobiles, not motorcycles.
GZ MotorSports offers many type vacuum pumps rating from 400 HP up to 2000+ HP.
You will not even get close to that range of needing a vacuum pump in a Sportster.
In fact, with the cheaply made aluminum case, a vacuum pump could actually destroy a Sportster engine according to this article.

You can use something much smaller as in a vacuum pump made for auto brake systems as bustert has mentioned before.
But even then, it needs to be monitored.


In road racing applications, and some drag racing instances where there is frequent throttle fluctuation from changing conditions or “pedaling” the throttle,
There may also be a need for a pop-off valve to help relieve built up pressure.
Under these circumstances, the engine can actually go from a vacuum situation to a positive pressure situation.
Generally, these pop-off valves have one-way operation and are typically placed on the valve cover.
They open at a specified pressure and allow crankcase pressure to vent to the atmosphere.


That's equivalent to on/off throttle to a lighter degree.
The crankcase fluctuates between faster and variable positive and negative pressures.

The article also says a that looser ring package works best with a vacuum pump.
Meaning more mods than just a pump are necessary for optimal performance.

The pop-off valve was introduced in 2010 on plastic oil tanks to help keep them from bursting under pressure.
60Gunner has a full account of the pressure generated and the affects thereof.
Would a pre-04 Sportster engine benefit from a pressure relief valve?
Only if it is already making too much pressure.
And then, that would need to be measured first which none has been so far, as I tell anyway.


This is what I got from the article.
Can you kindly tell me what I was suppose to get from it?
Maybe I missed something?
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  #360  
Old 31st July 2019
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Quote:
Originally Posted by dieselvette View Post
I have a theory about the "purposely leaky" check valves (stock has the "oil drain hole" , krankvent has the "ring" that can be modded) --- this could be simply a liability/safety concern.

While parked, there is the potential for pressure/vacuum buildup in the cc. With the crankcakse totally sealed, and potential for unburnt fuel vapors to exist in the CC (ever drained the oil on a car that wouldn't start, and found it full of gas?). Or, consider if there is fuel above the rings that could be drawn down if the cc is at vacuum.

The intentional "leak" at the check valve(s) allows the cc to stay equal to atmosphere when the engine isn't running. In stock, working form it apparently has little/no effect on the operation while running, and prevents oil from coming out.

Krankvent designers apparently believe the intentional leak has little effect, too, and if connected at the heads while leaving the stock umbrella assy in place, you would also retain the oil catching feature.

Or, maybe it's not a safety issue but a different reason.
As Four Speed mentioned, even without the drain hole, the umbrella will relax and let atmosphere in when parked.

Also, you can't control in which position the valves are in when the engine is shut off.
Most likely, both valves will not be closed as they are at TDC (compression) .
And if they are, you can't control carbon buildup that would let air seep past them.
Any air that gets past the valves on shut down will find way past the rings and equal out the pressure in the bottom end.
Same thing with unburnt gas, it'll seep past the rings also.
So the crankcase should never be totally sealed (although that has been mentioned before as happening due to a stopped up breather valve)
I figure vacuum bottled up in the bottom end would be most noticable just after shutdown before allowed to be equalized if there were a problem.

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.

In regard to the larger or smaller amount of air pulled in before the breather closes,
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?

edit:
I do believe the drain hole is a potential atmosphere input if there is no oil in there to drain.

This mod is more interesting now.

Middle Rocker Box Spacer (91-03)


This is a mod to curtail the issue of puking oil out the breathers.
86-90 engines do not have a crankcase breather valve incorporated into the rocker boxes.
However, the first answer would address other known factors for wet sumping.

This mod consists of;
Chamfering the umbrella hole to 60 degrees (included angle),
And drilling out the existing drain back hole to 1/8“.

To the extent the drain back hole is enlarged, it bypasses the umbrella valve.
Maybe 1/8” isn't enough to cause an issue,
But the umbrella valve is what keeps the air inhalation/exhalation to a minimum, And inhalation/exhalation is what carries oil out the breathers.
So you don't want to bypass it any more than necessary.

You could probably do the chamfer, but not the drain hole enlargement.
Then, if you still have the issue, you could also drill out the drain hole.

The rocker box middles use the same casting for both the front and rear cylinder.
And there's a facility for the umbrella valve on both ends of each middle spacer.
So you can try this, and if it doesn't work, just move the umbrella valve to the other end and use the rocker box middle on the other cylinder.
In other words, this mod is undo-able, a one time thing.

The umbrella hole is the one in the middle of the picture below.
The drain back hole is the tiny little hole to the right of the sideways 13 in the picture.


Another suggestion is to enlarge the tiny oil drain from ~.070 to .09375 and add threaded inserts as oil standoffs.


Looking at the pictures below, you can see 3 holes that are in a roughly oval shape area in the corners of the middle rocker box cover. (2 per rocker box, only 1 is used per cylinder)

With each downstroke, the air in the crankcase is forced thru the umbrella valve.
The air has an oil mist in it.
The oil is supposed it settle out in this little chamber and drain back to the cylinder head thru the tiny oil (bottom of oval area).


Slightly enlarging the little hole lets the oil drain back easier.
Air that enters this oval(ish) chamber has to go somewhere.
So it goes out the big hole on top, thru the breather bolts and out.
The threaded insert just provides a lip around the hole.
So any oil that drops out of suspension around the hole won't drain out the breather.


It just makes it a little bit harder for oil to go out the breather.
The inserts below were left overs from another project.
You can use anything that does the same thing.


You can buy a product online called “Slobber Stoppers”. https://www.ebay.com/itm/200917426709
It comes with threaded barrels similar to the threaded inserts below to eliminate oil mist from getting into the air cleaner.





In retrospect, isn't the Slobber Stoppers near the same concept as the smaller 04-up breather bolt hole?
The insert sets just under the roof of the box with slots for air to leave and oil is suppose to not climb the insert?
(even though that's inevitable)

Last edited by Hippysmack; 31st July 2019 at 04:21..
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