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

dieselvette 13th July 2019 04:47

Quote:

Originally Posted by Hippysmack (Post 5762083)
Big hole / small hole when it reverses should have no affect on how much air is pulled in before it closes.
But a certain amount will get pulled in as pressure reverses (until the breather closes).
Either is minimal unless the breather isn't working properly.

I'm thinking of something similar to intake/exhaust valve overlap where, if properly tuned, your exhaust will help pull in fuel during the overlap, due to the inertia of the exhaust flow. So in that moment when the umbrella is moving to close (out-flow stopped, inflow starting to come in) there is only a tiny volume of air (whats in the passage) that can come back - if the hole was not restricted, it could build up more inertia for more to come back in, even as the umbrella is still closing. But, now I changed my mind -

Quote:

Originally Posted by Hippysmack (Post 5762083)
When you see oil puking out the breathers at high RPM, remember, CC pressure is more equalized then.
Or should be.
The big change at higher RPM is blowby.
This adds to positive pressures and throws out the balance.

edit:Another change would be how fast the breather (umbrella) can close at higher RPM.

edit:
Changing to 1250 shouldn't change the balance (all things equal).
It may just make a stronger bond between positive and negative pressure.
(higher controlled windage)
So it may take a stronger force to change the balance.
The bigger bolt holes may not change enough to matter.

Once the CC pressure is negative if your umbrellas seal properly then the only way more air is introduced is from blow-by, which is always there - to a greater/lesser extent depending on your rings, compression, and RPM.

Blow-by helps scavenging, but causes CC pressure which, if severe enough, causes oil out of breathers b/c the out-flow is more/faster.

If the scavenge is falling behind and the tiniest pool of oil is high enough to touch the crank, then lots more oil "vapor". Then add to the recipe enough blow-by to cause the out-flow of this vapor to saturate the umbrella foam and/or coagulate and pool up near the breather = oil out the breather.

The fix is better scavenging and/or less blow-by, and keep your check-valves working. It's not about venting mods - although different venting schemes may solve different problems - that's just a bandaid.

I think this post by Aaron awsracing sums it up nicely:
http://xlforum.net/forums/showpost.p...4&postcount=22
and here
http://xlforum.net/forums/showpost.p...8&postcount=28
In fact, read the whole thread, then take a break, ponder it for a few days, and come back to this write-up. If there is one thing from this subject on sporsterpedia, it should be the breathing info from ASW's posts.

Side-note - I saw something, somewhere, about the vacuum inside the a/c vs. atmosphere, helping to pull out through the breathers. Wouldn't you think if there was enough vac here to have any impact, then you need a better filter? Your air cleaner should be = to atm.

Quote:

Originally Posted by Hippysmack (Post 5762083)
Well, the squirters arrange for more oil to be in the sump at once on both upstroke and downstroke (from the feed pump).
They also decreased backpressure on the oil filter with the added outlet downstream.
But the pump will only give what oil it will give (positive displacement).
Feed volume (to the sump) is based on RPM, (restrictions already passed).

That's an interesting point - same volume oil pump, but added the squirters. What gives? I suppose the amount from the squirters is tiny, compared to the overall pump volume.

Hippysmack 13th July 2019 05:20

I agree I need a break.
Been at it most of this week.
I kinda go into a dark place with this subject with total focus.

Most of this thread's beginnings are comments from Aaron and many others more knowledgeable than me.
But most likely, I haven't read it all yet though.
I wanted to establish a beginning base but left the credits out for general discussion.

I'll go thru your links also.
Chances are I've already been through these and chances are I missed something.

But that's why I have settled on only doing mods if you need them.
There are so many brilliant ideas on this forum but they aren't for everybody.
I've tasked myself with knowing the difference.
Kinda like hitting myself in the head with a baseball bat....again, and again..:headbang

edit:
I wanted to add I mean no disrespect to the original posters.
I've taken bits and pieces from threads and pulled them together here and in the pedia.
Actually it's double the work.
But for my little brain it's a lot to take in.
Funny thing is I have put a lot of my own thought into this.
Then I come across a thread from Aaron or others to find I was at least sometimes in the ball park.
As the old saying goes, 'teach them how to fish....'.
I guess I'm learning how to fish. :)

Also, I'm learning a lot more this way than fuddling through the animosities of others.

harley506d 13th July 2019 08:23

Quote:

Originally Posted by Hippysmack (Post 5762208)
That looks nice and tidy.
I have a question about the bend in the line before the filter.
What, if at all, have you noticed in the line at that bend?

I'm thinking oil / condensation could settle there even if it doesn't run up to the filter.
I guess better put, ever pulled the filter to inspect the line near the bend?

I like the 'Y' down low instead of the horseshoe up with only one side running down for the same reason.

I take the pipe off at the filter and straighten the bend out to drain. Only had a small drop of water, never any oil.
Enjoying the work you are putting in on this breathing subject!

Hippysmack 13th July 2019 16:54

That's good to know.
I've seen many configurations up, down, under, over and wondered what the affects would be.
Some say don't put a filter on the end, some do.
With the filter down, some report it getting full of oil so they take the filter off and just let it drip.
Chain driven models, some let it drip on the chain.
I think water or oil that would settle in the bend when cooled down would get heated back up, pulled back into suspension and sent out the end anyway.
That may be a little more complicated if there were several low bends though.
Then you could just re-route if needed.

bustert 13th July 2019 18:11

as you mentioned, auto's used exhaust pulses to pull away c/c vapors, drag engines were an example of this. could it be used on the sporty?? well if you had a venturi tube and orifice/check in the header, sure it can be done, commercial engines used that method, waukesha being one of them.
do you really need vacuum to make power??? maybe IF your are trying to squeeze blood from a turnip but reality is, street design doesn't need it.
there is a whole complete science on piston & rings.
what a street engine needs is diff'l pressure. a mfg only needs to meet epa's regs where they say most pollution occurs. it is impossible to make a engine 100% compliant over the entire range since the engine itself develops power diff over the range.

Hippysmack 13th July 2019 18:21

Yeah I think a vacuum pump is not necessary on a street engine.
The problem occurs when us street guys get to feeling our oats.
There is a certain speed where a street engine is asked to step up to race conditions.
I really believe that is the root of a lot of the problems.

Actually I have read the above link from Aaron on the breather hole size.
But I had flow on my mind at the time.
And I said I probably missed something, which I did.

The small hole in the bolts does help scavenge in theory.
The pressure inside builds a little more from that restriction.
But it only bottles up pressure on downstroke and only to a point.
That little more positive pressure is an extra push on the lower end toward the sump scavenge port.
So it is serves a couple purposes.
It does raise the output flow pressure at the vent which speeds the flow out of the heads.
It would seem the extra pressure inside would tax power slightly.

bustert 13th July 2019 18:23

in the past, hd tried to move as much c/c vent out of the engine as possible but with todays set of rules, this had to change.
in a post i made moons back, i commented on the 01 breather in regards to oil in the filter. what i believe was happening is lazy flow.
at wot, air flow through the filter can is great enough to pickup the vent from the bolts. however, when you push the machine and decrease rpm, air flow slows down. piston speeds are still up so vent is still up. if the machine was pooling oil, and if the oil was not draining back out of the coalescer, oil would be discharged into the cleaner.
when air flow slows, heavier molecules of water and oil drop out.
i believe it to be more water than oil but you only see the oil for the obvious reasons.
i too had seen this but i redirected to a place where air flow is at it highest through all ranges, aka, the carb throat.
like an oil debate, c/c vent into the engine will go on but look at history, when the engine is running as designed, no harm comes from it. we all age, shoot that is why depends are made for, leaky plumbing. water does no harm, i used to run water injection.

Hippysmack 13th July 2019 18:33

I hadn't thought of that.
I do know on/off throttle can cause oil to puke out the A/C.
I've experienced that in the past.

But I hadn't considered intake pulling in air from the vent, only the vent choking into it.

bustert 13th July 2019 18:42

now i am going to address the bolts.
first of all, we have to consider
1. boyles law
2. charles law
3. bernoulli law

and yet, only parts and pieces can apply.
the bolts cannot be considers an orifice as in venturi effect and gas measurements. they must be looked at as series restrictions.
it is here bernoulli theorum applies.
in the gas compression for shipping natural gas, compressors are often fitted with orifices or series restrictions.
just like an engine, when the valves close on a compressor cyl, the is a reversion and this upsets gas flow and increases energy needs to more the gas.
by finding the resonance frequency of the pulse, we can add a plate that will restrict or slow down the pulse which make the gas flow more freely.
with the changes to the hd engine, a new sheriff is in town. hd cannot just vent as in the past.
however, within their design, they can control the pulse. by r&d they know where the frequency comes in at so they slow down the flow so a more constant flow can be achieved. will this raise c/c pressure, sure but all we need is a diff'l no a vacuum. offshore, we could set c/c pressure to positive of negative according to where the engine was placed, we could set value of such. we did not try to achieve max reduction but tried to run a negative 3>5 on the c/c.
anything past that would not be of any benefit and would draw in more vent to the induction tract. also, you have to provide inlet to c/c air to purge it.
here hd does not do such.
you mentioned that the umbrella could float and i believe you are correct, as long as vent pressure is high enough to pass through, it will, thanks in part to the reduce breather bolt restriction.'
as a side note, less gas flow through the system has a positive effect on keeping oil and gas from mixing to begin with.
hd designed for a range and if the rider rides outside the range, then he has to make a better mouse trap, hd is doing as designed.
man, many typos, second keyboard going south.

dieselvette 13th July 2019 18:43

Quote:

Originally Posted by bustert (Post 5762400)
in the past, hd tried to move as much c/c vent out of the engine as possible but with todays set of rules, this had to change.
in a post i made moons back, i commented on the 01 breather in regards to oil in the filter. what i believe was happening is lazy flow.
at wot, air flow through the filter can is great enough to pickup the vent from the bolts. however, when you push the machine and decrease rpm, air flow slows down. piston speeds are still up so vent is still up. if the machine was pooling oil, and if the oil was not draining back out of the coalescer, oil would be discharged into the cleaner.
when air flow slows, heavier molecules of water and oil drop out.
i believe it to be more water than oil but you only see the oil for the obvious reasons.
i too had seen this but i redirected to a place where air flow is at it highest through all ranges, aka, the carb throat.
like an oil debate, c/c vent into the engine will go on but look at history, when the engine is running as designed, no harm comes from it. we all age, shoot that is why depends are made for, leaky plumbing. water does no harm, i used to run water injection.

Yep, and don't mean to start an "oil debate" here but the extra 2-3hp that Aaron found on the dyno makes it pretty clear. Admittedly I was still running mine into the carb throat (as with the SE air cleaner) because I didn't care about the HP and wanted to keep things simple. Really, my carb throat and intake manif were always very clean. So whatever I've said in the past, I don't think its that big of deal to vent into the carb. But I'm going to vent mine external because I want to improve MPG.

Water injection the idea is to cool the intake charge, making more dense etc., you know how that works. But the gasses coming out of your vents, no matter how wet, are combustion gasses that are hot and deficient of oxygen. Really the only moisture is condensation and is very inconsistent, so it would be difficult to tune for the advantage it would bring, if it did.

Hippysmack 13th July 2019 18:57

You forgot My Law, "Damn if I know" :laugh
It's that control that you mentioned which really can only be adjusted through testing.
And every engine is different.


I take Aaron's testing to heart about the breathers.
With all the different ones mentioned on the forum,
The results are pretty much the same.
It works, but there isn't any suggestions that it works better than the other.
(on a daily driver that is)
I'm not looking for a few extra ponies as my racing days are about done.
Although I do enjoy opening up every now and then.

Hippysmack 13th July 2019 19:12

Quote:

Originally Posted by dieselvette (Post 5762409)
Really, my carb throat and intake manif were always very clean. So whatever I've said in the past, I don't think its that big of deal to vent into the carb. But I'm going to vent mine external because I want to improve MPG.

Water injection the idea is to cool the intake charge, making more dense etc., you know how that works. But the gasses coming out of your vents, no matter how wet, are combustion gasses that are hot and deficient of oxygen. Really the only moisture is condensation and is very inconsistent, so it would be difficult to tune for the advantage it would bring, if it did.

I'm still running the ham can with a K&N filter and it is usually pretty clean inside the carb.
I want to move the vent from the carb to see the results.
Reportedly there is a little more power in that but frankly, I'm at a good point on power for what I use.
I've always liked to have power if I need it but don't always push it.

I once had a car turn in front of me to get onto the interstate on-ramp.
With the carb tuned well enough and power behind, I was able move fast enough to avoid their bad decision.

I couldn't have done that on the Kawi.
I feel if running the vents in the A/C was actually detrimental to the engine, the MoCo would have engineered some other way to meet EPA specs.
They have a stake in that.

All these mods we do sometimes has a purpose and sometimes it's just cause we want to.
Or sometimes we do them cause we're told we need to by someone else that felt they needed to.
I really don't think any of us are re-inventing the wheel though.

bustert 13th July 2019 20:25

you know at one time, they said power and egr could not happen, well it did. but thanks to the computer, my last 3 cars did not have egr.
you know pulling 3>4 extra hp on a dyno has virtually no real world effects on the street. within design, c/c vent is harmless. now once you factor in wear and etc, oil introduction can cause many issues and detonation is one of them. but hey!!! oil induced detonation can come from other sources so the push to design oil that will kill the potential.
you can have the 3>4 hp but i will take after peak power every day and win.
if you have two identical cars but one carries the hp after peak further, it has an advantage. if i can pull for grins and giggles 500 more rpm that puts me further down the road per ratio.
water injection does nada for intake charge, not enough time to make a hoot
the big deal is that it cools the combustion process and gives a better burn. it also reduces emissions and you can gain more power per given charge.
bosch i believe has a system for boosted engines that not only increases power but at better mpg as less fuel is needed.
another thing is that carbon is held at bay especially so back when i ran it since todays fuel produces little.

60Gunner 13th July 2019 21:37

Quote:

Originally Posted by harley506d (Post 5762185)
Had to search for pic! Filter just tie-wrapped to underneath airbox. I suppose the motor is not really "stock" as i have done the jetting etc. But having totally screwed up my beloved 1340 FXRT years ago , i am leaving this alone! Gives me 50+U.S. mpg, and goes to 100mph easily enough, (stock exhaust at the moment) it's good enough for me!

https://i.ibb.co/HGhQgcC/air-box-002.jpg

What jetting? If you added no more air by using a better AC and it sure isnt breathing very well using the stock exhaust, what jetting did you do?
Seriously, be nice to your motor and let it breath. It's not about how fast it can go. It's about not choking the piss out of it.
No point adding more in one end if it can't make it out the other.

Hippysmack 13th July 2019 21:45

Quote:

Originally Posted by bustert (Post 5762408)

the bolts cannot be considers an orifice as in venturi effect and gas measurements. they must be looked at as series restrictions.
Correct. The restriction is the idea.

by r&d they know where the frequency comes in at so they slow down the flow so a more constant flow can be achieved.
will this raise c/c pressure, sure but all we need is a diff'l no a vacuum.
Agreed the smaller hole slows down the immediate outflow, until higher pressure overcomes the restriction.
The higher pressure is still expelled as before only faster. The result is more air/oil mist against internal parts and pressure pushing sump oil.


also, you have to provide inlet to c/c air to purge it.
here hd does not do such.
you mentioned that the umbrella could float and i believe you are correct,
as long as vent pressure is high enough to pass through,
it will, thanks in part to the reduce breather bolt restriction.'

Exactly.
The MoCo has some fine tuned engineering that isn't published, to us anyway.
There is a reason for every change they make.
Some, of course, is for saving money.
Some are to compete in the market.
Some are candy to make a sale.
But some is for the good of the bike.
I think that last one gets looked over for the most part.

And the inlet to purge is ring gap.
If you breath into a balloon and then inhale, all you're doing is inhaling your expelled breath.
The only movement is your breath going back and forth.
The blowby adds to your expelled breath which creates more going out that came in.
The balance has changed.
In addition, if the breather closes at upstroke, outside air is blocked off as the piston rises.
Leaving the purge air as blowby only.
If the breather doesn't close, it also brings in outside air added to the blowby which creates a bigger purge.
The imbalance is compounded.

I also understand that once enough vacuum is achieved to allow good ring seat, anything more is not accomplishing anything extra.
Except slowing down the push toward sump oil and lessening suspension oil, which has to be compensated for elsewhere.
That's the compensation that needs to happen before just throwing in a vacuum pump and believing you fixed a problem.

Piston / cylinder / breather etc. upgrades can change the parameters of OEM design.
And that's where the mods come in to compensate for what the MoCo didn't design for.



Hippysmack 13th July 2019 22:20

Quote:

Originally Posted by bustert (Post 5762425)
you know at one time, they said power and egr could not happen, well it did.

pulling 3>4 extra hp on a dyno has virtually real world effects on the street.

within design, c/c vent is harmless.

now once you factor in wear and etc,

you can have the 3>4 hp but i will take after peak power every day and win.

I never had the taste for EGR systems. Too much of a PITA to work around.
But I've never been in the money to be concerned about 3>4 extra ponies either.
That doesn't make me want to learn any less though.
So far, I've been focused on a healthy engine.
As mine isn't showing any concerns of that yet.
But that is the reason I usually dump my V-8 breather hose to atmosphere.
Even on a new build.
Time will wear the rings and excess blowby will happen.
I just cut to the chase.
But the Sporty engine and a V-8 are two different animals.
But when it gets that bad, the right answer is new rings, seals or rebuild.
Even though I have been known to run it til it drops (out of poor finances).
But no, excess blowby from wear, rings or valves, doesn't need to go into the A/C.

I guess water injection would be equal to a cool can with perks?

3>4 hp from the jump for a 1/8, off peak for 1/4? :D

Toejam503 14th July 2019 00:07

The PCV was one of the first items to be used for "emissions" on vehicles, back in the '60's. It kept the oil vapors from venting to the atmosphere. Plus side was it made the air charge slightly denser and helped with added lubrication to the intake side of the engine cycle. I feel this may be even more important, nowadays, since there are fewer and fewer lubricating properties in today's gasoline.
As far as water injection goes, this was an option on Cadillacs and Buicks in the 50's and '60's. The explanation was it kept intake temps lower (less chance for run-on and every part of the country had different octanes), kept the cylinders/pistons/valve faces from getting too much carbon build-up and the bonus was 10mpg verses 7-8mpg. They stopped offering it when there were too many customer complaints of constantly filling the "glass" jar with water and cold temperature changes. More trouble than the actual advantages in daily driving.

Hippysmack 14th July 2019 00:52

It sounds like a lot of trouble maintenance wise.

bustert 14th July 2019 00:57

actually according to bernoulli the pressure does not exit faster. when the pressure hits the restriction, pressure must rise in order to go through so that stifles flow. now once the pressure has passed, there must be a pressure drop. here is where it gets tricky. since there is a decrease in pressure, there is an increased probability of drop out and the further from the opening, the greater the drop, reason why they put drip bottles on instrumentation.
you are right in that the increased pressure does cause increase flow through the orifice but the effect would be nil. like changing a plate in a orifice meter, higher pressure requires a larger opening. but then again we are getting into venturi and not restriction properties.

bustert 14th July 2019 01:00

once again, flow time does not support cooling intake charge, major effect is lowering combustion temps. if you are drawing in ambient air and the jar is ambient or perhaps hotter from engine bay heat, it cannot cool the intake air.
in the winter, 50/50 with alcohol.

Hippysmack 14th July 2019 01:54

Yeah I kind of see that if we were talking flow properties.
But the pressure does rise with a tax on the pistons and compensated at the throttle.
So the restriction does affect the source.

harley506d 14th July 2019 08:34

Quote:

Originally Posted by 60Gunner (Post 5762432)
What jetting? If you added no more air by using a better AC and it sure isnt breathing very well using the stock exhaust, what jetting did you do?
Seriously, be nice to your motor and let it breath. It's not about how fast it can go. It's about not choking the piss out of it.
No point adding more in one end if it can't make it out the other.

All i did re jetting was to clean up the over lean factory settings.
It now has...
45 pilot.....it came with this, i believe the stock was 42.
170 main. ....stock 160
N65 needle.....stock was N9EY with 1 shim(probably added by P.O.)
Stock filter.

So only very minor tweaks really just to clean it up a little.
The problem is, better breathing equals more noise (usually a lot more), which i hate.
If i had the money, then i may go for a S&S teardrop air cleaner (for looks alone) and Supertrapp exhaust (but i would prefer to keep a 2 into 2 system) as that seems to be the quietist available. But that would be putting the best part of 2K into the bike.

60Gunner 14th July 2019 13:55

Quote:

Originally Posted by harley506d (Post 5762524)
All i did re jetting was to clean up the over lean factory settings.
It now has...
45 pilot.....it came with this, i believe the stock was 42.
170 main. ....stock 160
N65 needle.....stock was N9EY with 1 shim(probably added by P.O.)
Stock filter.

So only very minor tweaks really just to clean it up a little.
The problem is, better breathing equals more noise (usually a lot more), which i hate.
If i had the money, then i may go for a S&S teardrop air cleaner (for looks alone) and Supertrapp exhaust (but i would prefer to keep a 2 into 2 system) as that seems to be the quietist available. But that would be putting the best part of 2K into the bike.

The only thing lean from the factory was pilot. Possibly the needle. The main was actually a bit fat.
When I opened up my 1200 with a free flowing AC and exhaust the 42 pilot went to 45 and the needle went to a N65C. The stock 180 main stayed.
If upped everything on a completely stock motor, AC and exhaust included, you're running pretty rich up top.
But I don't recall a stock main being 160. I could be wrong in a Euro model tho.
Regardless, you're punishing your motor with that exhaust.if you ever actually run the main and I'm not quite sure I understand your reason why. Because you feel by doing so permanently damaged another bike?

bustert 15th July 2019 03:55

we are talking manifold charge, impossible for water to evaporate in short time frame. the cooling effect is within the cylinder.
i ran the holley system on my dodge 440, know how it works. also water injection must be controlled on a variable speed engine unlike aircraft with a set engine speed. the holley injected via temp and flow rate controls.
spray bottle and spritzing a engine is poppy-cock, will not decarbon and engine, it MUST be over time, aka, running at street level, garage level spritz is a waste of time, better to use GM decarbon fluid IF you can find it. BTW: better do it outside and it will gag a maggot if not kill it. when unleaded fuels came out GM discontinued it.

Hippysmack 19th July 2019 17:50

When I came back from a spirited ride today, I pulled the oil cap off to check for aeration.
There was none.
But I did notice I lost app 1,000 RPM with the cap off.
What does that mean?

edit:
The only thing that makes sense to me is a higher air/oil density due to more oil picked up in suspension with the engine breathing both in and out.
...at idle.
I have the 07 oil pump and stock breathing system with a K&N filter.

bustert 21st July 2019 03:59

not following
lost 1000 rpm at idle or running down the road
on the auto side, if you remove the oil fill cap, the engine will run badly as it screws with the calibration.

Hippysmack 21st July 2019 04:22

When I got back and just before shutting her down, I pulled the oil cap just to see what I could see.
The engine stumbled briefly and the tach went down to about 950 (idle was 1050).
I thought the gas tank was low for a second.
Standing there with the cap in one hand and my heart in the other, I shut the engine down.
Scratched my head, put the cap back on and fired it up.
Idle was fine.

Then I pulled the cap back out with the engine idling and that's when I noticed I lost app 1000 RPM from watching the tach go down.
Through researching threads, I found that decman said it happened on his S model when hot but not when cold.

Also cantolina mentioned once the engines don't like that.

I believe it throws CC pressure out of kilter with the cap off as the CC is open to atmosphere at that point.
Funny it not happening on a cold start?
Cold oil (room temp) doesn't suspend as fast as hot oil?

My theory:
With the oil cap off the tank on a hot idling engine, the engine speed drops app. 1,000 RPM at idle.
This is the same as having a bad breather valve opening but not closing.
Oil doesn't puke out the tank since higher density suspension oil comes up the return line from the sump.
The suspension fluid and return oil together in the line helps to separate the oil back out of suspension by the time it reaches the tank.
The bulk of air / oil mist is generated in the crankcase, not the cam chest where the vent line to the tank is.
(leaving what comes out the top of the oil tank to be nothing but air).
The higher air/oil density drags the flywheels and more oil is picked up in suspension with the engine breathing both in and out.
The engine responds at idle from the higher load on the wheels.

bustert 21st July 2019 14:36

so you are saying flooded flywheels?
and the engine dies?
instantaneous results or takes a little time?
i will have to see if mine does that, but then again i have checked oil circulation and never experienced this so i will flog it to see.
however, i run cold oil temps for cooling so that may have something to do with it.

Hippysmack 21st July 2019 15:35

When I first pulled the cap, the engine almost died.
After firing back up and pulling the cap, it stumbled but ran rough on 950 RPM.
It was an instantaneous response to pulling the cap.

I am not saying it flooded the sump but rather it seemed to have picked up drag.
As if more oil had suddenly got wrapped around the wheels.
I didn't notice any surge or lack of scavenging in the tank.
I'm also using the Buell wheel assembly with slots in the wheels.
Maybe that's got something to do with the speed of response?

dieselvette 21st July 2019 20:03

Quote:

Originally Posted by Hippysmack (Post 5763952)
Standing there with the cap in one hand and my heart in the other, I shut the engine down.

lol have you ever considered being a writer? That line just struck me as "quotable" - right out of a classic novel.

Quote:

Originally Posted by Hippysmack (Post 5763952)
Through researching threads, I found that decman said it happened on his S model when hot but not when cold.

I'm sure he's right but that was one bike - there may have been unknown circumstances that caused his bike to act like that. Could have happened to others too, but I don't know if it holds any weight without thoroughly ruling out all other possible issues, on every afflicted bike.

Quote:

Originally Posted by Hippysmack (Post 5763952)
I believe it throws CC pressure out of kilter with the cap off as the CC is open to atmosphere at that point.

It would certainly throw things off - to a greater or lesser extent depending on the size & length of your tank-cc vent connecting line.

I defer to Aaron's experiments on his bike a long time ago (referenced in a different thread somewhere? Posted by Aaron I think - could have been in a different forum?)

Also based on his explanations, I believe the CC pressure is pushed out the breathers (and goes to slight vacuum?) within the first few revolutions on startup - cold or hot; and stays that way (fluctuations, of course) as long as everything is working correctly.

Nonetheless i'm glad you brought it up because now I'm inclined to thoroughly inspect my oil tank for air leaks. (That's easy to do, and eliminates variables in diagnosing my wetsumping problems).

Quote:

Originally Posted by Hippysmack (Post 5763952)
Oil doesn't puke out the tank since higher density suspension oil comes up the return line from the sump.

Why would oil puke out the tank anyway, unless it was plumb full (or had a crappy straw for a oil cap)?

Bottom line, I don't think operating temp has much to do with it, except that ring seal may be better/worse at a given temperature, and probably only significant if you have an actual ring-seal problem.

Quote:

Originally Posted by Hippysmack (Post 5763952)
The suspension fluid and return oil together in the line helps to separate the oil back out of suspension by the time it reaches the tank.
The bulk of air / oil mist is generated in the crankcase, not the cam chest where the vent line to the tank is.
(leaving what comes out the top of the oil tank to be nothing but air).

all true - oil tank somewhat acts as an oil/air separator.

Quote:

Originally Posted by Hippysmack (Post 5763952)
The higher air/oil density drags the flywheels and more oil is picked up in suspension with the engine breathing both in and out.
The engine responds at idle from the higher load on the wheels.

Quote:

Originally Posted by Hippysmack (Post 5764036)
When I first pulled the cap, the engine almost died.
After firing back up and pulling the cap, it stumbled but ran rough on 950 RPM.
It was an instantaneous response to pulling the cap.

I am not saying it flooded the sump but rather it seemed to have picked up drag.
As if more oil had suddenly got wrapped around the wheels.
I didn't notice any surge or lack of scavenging in the tank.
I'm also using the Buell wheel assembly with slots in the wheels.
Maybe that's got something to do with the speed of response?

I don't think it has anything to do with oil or oil mist; rather, it has everything to do with air pressure. If you have bad umbrella valves (or otherwise let too much air back in - anywhere - on upstroke, then the pistons have to push that air back down, and they're working against air pressure. This has a few implications: a) more oil is pushed past the rings, you burn oil; b) power is lost due to your CC being an air compressor (even at idle, so it slows down/dies) and c) oil is more readily (better) forced up the passage out of the CC into the scavenge, which lessens wet-sumping.

Now, that doesn't mean oil burning = incorrect venting: oil use could be due to any number of reasons of course. Also, you could still have wet-sumping problems in spite of high CC pressure, if other things aren't right - and to the novice it may be difficult to sort out which problem they have (high CC pressure, wet sumping) especially if they have either/both in different/similar scenarios - and even worse if they have more than one thing that needs to be fixed (any of the above: bad umbrella valves, bad rings, oil tank with air leaks, exhaust valve seals?, plugged oil tank-cam vent line, etc.)

It also doesn't necessarily mean that you should increase your CC pressure to fix wetsumping. Wet-sumping is simply a matter of the pump not moving enough out. Bearing in mind that the scavenge section often pumps oil+air (which is compressible), wet-sumping could happen if a) pump is inadquate size for volume of oil+air present; b) pistons on downstroke don't move enough volume up through the passage to scavenge port (e.g. when CC pressure has an easier path OUT elsewhere) c) tank vent back down to cams is restricted; d) oil tank pressure high for other reasons (vent line is OK, but cams & top end at higher pressure due to improper venting or bad seals).

bustert 21st July 2019 21:23

well, it rained so i could not flog it so the first run was at 130*f oil temp and the engine did drop 100 rpm after a few seconds.
on the return, the roads were drier, have to be careful as she'll break traction. i was able to get temps a tad over 140*f and the rpm drop was more pronounced but did not die.
the way she acted did not seem to be flywheel related as i played around with it.
just me but i seem to think it was more of a mixture issue since i could alter the way it ran playing with the oil tank.
a rich mix will be sluggish and since we tune cleaner on, the carb will react to anything that changes flow within the cleaner.
when the tank is opened, it vents the majority of the pressure out of the engine, mine was huffing pretty good. with this pressure not going into the cleaner, it has to pull harder through the media with the resultant effect of a richer mix.
besides, the oil will still transfer out the compartment since flow is to the cam chest.

60Gunner 22nd July 2019 00:46

I can relate first hand that introducing air has this effect and the higher temps are a result as well. I believe it's partly because of the crank doing the backstroke in oil, pistons working harder, and the oil being suspended in the heads longer and getting hotter. Higher rpms magnify this issue greatly. I think the crank swimming in oil comes last after extended high rpm. The pistons working harder and oil not draining from the heads as quickly are immediate consequences.
Increased air pressure is NOT good. You wouldn't think failed umbrellas would have such a big impact but I'm convinced this is the case.

Hippysmack 22nd July 2019 01:00

Quote:

Originally Posted by bustert (Post 5764097)

the first run was at 130*f oil temp and the engine did drop 100 rpm after a few seconds.
i was able to get temps a tad over 140*f and the rpm drop was more pronounced but did not die.
the way she acted did not seem to be flywheel related as i played around with it.
just me but i seem to think it was more of a mixture issue since i could alter the way it ran playing with the oil tank.
a rich mix will be sluggish and since we tune cleaner on, the carb will react to anything that changes flow within the cleaner.
when the tank is opened, it vents the majority of the pressure out of the engine, mine was huffing pretty good. with this pressure not going into the cleaner, it has to pull harder through the media with the resultant effect of a richer mix.
besides, the oil will still transfer out the compartment since flow is to the cam chest.

That would suggest the intake of the carb gets a substantial amount of air from the CC vents.

Some oil will still transfer to the cam chest for sure.
Lighter density oil will transfer faster than heavier density oil.
Heavier density oil will get slung into the crankcase walls as well.
So you at least did notice a change with the oil temp higher.
I realize that only a couple folks have mentioned this but I simply couldn't find many other's comments on the subject.

I didn't think to play around with the cap to get varying degrees of change.

There may be several things happening. In looking at the angles;
The vents are on/off so if that were the case,
Velocity in the intake could also be on/off on a normal day on every downstroke depending on the condition of the breathers?
As in both in different states of hardness / flexibility.
Then compensated by an increase through the media during out of sinc moments.
The vents don't put out that much air pressure normally I'd think.
Although the vent air does tax the intake track.

On the other hand,
The breathers are opened upon downstroke before much cylinder fill.
With the oil cap off, this relieves the pressure under the pistons faster during downstroke (wider escape but still traveling up the 1/4" vent hose).
In theory, better ring seal on downstroke also (increasing cylinder fill velocity)?
In that case, wouldn't the CV carb react in kind?

I'm curious about the oil temperature.
I'm leaning toward more dense air/oil mix since I considered what came first, the chicken or egg.
Apparently colder oil temps are less taxing on the issue.
Oil suspension is higher (faster) with hotter oil, lower (slower) with colder oil.
We speak of hot idle as the engine barely turning.
But the truth is 1000 RPM is still humping it. It'd be more visual if the engine case was transparent.

I can see my SBC crank pulley moving at 1000 RPM and then spraying oil on it.
It would immediately sling oil several feet each direction.
But the Sportster wheels sling oil inches away to the case wall cylinders/piston unders where some falls back on the wheels.
Higher suspended oil increases the oil density of the air/oil mix.
I don't think wet sumping is happening as I see the oil returning without issue.
Oil mist is slung around by the wheels by default of the machine.
But more dense air/oil suspension is heavier (what is swirling around the wheels).

If it's simply the mixture or balance of crankcase pressure, then the MoCo definately accomplished a change with the smaller breather bolt holes.
To be able to manipulate the mix simply by moving the oil cap closer or farther away from the opening proves how sensitive the engine is to CC pressure changes with air moving into the engine also.

Hippysmack 22nd July 2019 02:04

Quote:

Originally Posted by dieselvette (Post 5764078)
lol have you ever considered being a writer?

I'd go broke considering the time it takes me to write a paragraph. :laugh

I'm sure he's right but that was one bike - there may have been unknown circumstances that caused his bike to act like that. Could have happened to others too, but I don't know if it holds any weight without thoroughly ruling out all other possible issues, on every afflicted bike.

Agreed, that's why I'm bringing it up is to see if others experience it also.

It would certainly throw things off - to a greater or lesser extent depending on the size & length of your tank-cc vent connecting line.

All vent lines to the tank are 1/4" if OEM.

Also based on his explanations, I believe the CC pressure is pushed out the breathers (and goes to slight vacuum?) within the first few revolutions on startup - cold or hot; and stays that way (fluctuations, of course) as long as everything is working correctly.

Yeah, with the engine shut off, the umbrellas do not seal off from outside air.
The engine is at atmosphere.
Fire it up and there is a pulsating positive pressure on downstroke and slight vacuum on upstroke.
But that's ever changing with blowby added.
There is never a set vacuum inside while running. It's all variable.


Nonetheless i'm glad you brought it up because now I'm inclined to thoroughly inspect my oil tank for air leaks. (That's easy to do, and eliminates variables in diagnosing my wetsumping problems).

I can't seem to leave this article by JohnK about the inner sleeve breaking on the 04-up caps:
http://sportsterpedia.com/doku.php/techtalk:evo:oil04b
What does that spring do and is the probe sticking down into the tank hollow?
http://sportsterpedia.com/lib/exe/fe...5_by_johnk.jpg
Makes me wonder if the O-ring seal has something to do with rubbermount heat and oil consumption.



Why would oil puke out the tank anyway, unless it was plumb full (or had a crappy straw for a oil cap)?

It doesn't, I'm looking for reasons why it doesn't.
Then reasons why Deimus's first mod didn't work (PCV on oil tank vent) and consequently why other folks that did that mod where it did work (somewhat).


Bottom line, I don't think operating temp has much to do with it, except that ring seal may be better/worse at a given temperature, and probably only significant if you have an actual ring-seal problem.

Operating temps give clues to conditions that end up being bad for the engine.


all true - oil tank somewhat acts as an oil/air separator.
I don't think it has anything to do with oil or oil mist; rather, it has everything to do with air pressure. If you have bad umbrella valves (or otherwise let too much air back in - anywhere - on upstroke, then the pistons have to push that air back down, and they're working against air pressure. This has a few implications: a) more oil is pushed past the rings, you burn oil; b) power is lost due to your CC being an air compressor (even at idle, so it slows down/dies) and c) oil is more readily (better) forced up the passage out of the CC into the scavenge, which lessens wet-sumping.

Agreed, the extra air intake is harder on piston downstroke.
But why is it even harder when the oil is hot?


Now, that doesn't mean oil burning = incorrect venting: oil use could be due to any number of reasons of course. Also, you could still have wet-sumping problems in spite of high CC pressure, if other things aren't right - and to the novice it may be difficult to sort out which problem they have (high CC pressure, wet sumping) especially if they have either/both in different/similar scenarios - and even worse if they have more than one thing that needs to be fixed (any of the above: bad umbrella valves, bad rings, oil tank with air leaks, exhaust valve seals?, plugged oil tank-cam vent line, etc.)

Agreed, one problem begats another.

It also doesn't necessarily mean that you should increase your CC pressure to fix wetsumping. Wet-sumping is simply a matter of the pump not moving enough out. Bearing in mind that the scavenge section often pumps oil+air (which is compressible), wet-sumping could happen if a) pump is inadquate size for volume of oil+air present; b) pistons on downstroke don't move enough volume up through the passage to scavenge port (e.g. when CC pressure has an easier path OUT elsewhere) c) tank vent back down to cams is restricted; d) oil tank pressure high for other reasons (vent line is OK, but cams & top end at higher pressure due to improper venting or bad seals).

There is a balance I'm looking for that has to be maintained.
I need data for a more complete understanding.



dieselvette 22nd July 2019 02:13

Sorry if this sounds blunt or curt, but you guys are really confusing the issue. I can assure you that the carb and a/c have nothing to do with it. The carb flows, say up to 200 CFM? The air filter itself, if stock size but better flowing(K&N) can easily flow enough air to make 100hp. There is NO measurable pressure difference inside/outside the filter element itself. The airflow out the vents is negligible compared to these factors.

The vents however, if ported into the carb throat, DO deliver a small amount of "bad" air to the intake. Not much, but enough to rob a couple hp in the right conditions. Also they deliver some oil to the intake when a venting problem occurs.

Edit: HD vents into the a/c to pass EMISSIONS, to the detriment of performance, and not for venting dynamics.

Hippysmack 22nd July 2019 02:20

That's kinda what I alluded to but I never discount bustert.
He's a good thinker.

Hippysmack 22nd July 2019 02:29

That brings me to the 2010 oil tank.
Supposedly this was the year the MoCo installed the 10psi pressure relief in the oil tank.
Anybody got one that exploded can split it and take pics of the innards?
I'm curious where and how it's installed and it's function.

dieselvette 22nd July 2019 04:36

Quote:

Originally Posted by Hippysmack (Post 5764172)
What does that spring do and is the probe sticking down into the tank hollow?
Makes me wonder if the O-ring seal has something to do with rubbermount heat and oil consumption.

OEM cap like the one pictured - no - the end is sealed, the entire gray piece is one mold, as long as the main oring is good you're OK, and that's all you need to cap the tank. The rest is just there to make it fancy.

The O-ring not sealing - seems like it would take a heckuva leak though (like maybe NO oring at all) to cause a noticeable issue. NEED to read Aaron's experiment with the Buell. I found it here:
http://xlforum.net/forums/showpost.p...5&postcount=34

Similar it is, to your removing the cap at idle. You've just opened a 1/4" 3-ft hose from cam chest to atmosphere. Differences you were at idle, and connected to cams not crankcase. It's a moot point tho, because if you suspect oil tank/cap leak you wouldn't diagnose it by looking at your venting system. It is easy to do a tank leakdown test with a mity-vac (or something) on the vent line - if tank is sealed, it's sealed; if not, then find the leak and fix it. After testing/fixing that and you still suspect venting issues, forget the tank and carry on with other checks.


It doesn't, I'm looking for reasons why it doesn't.
Then reasons why Deimus's first mod didn't work (PCV on oil tank vent) and consequently why other folks that did that mod where it did work (somewhat).

I still don't follow. The tank can't puke oil out because the oil level is *inches* down from the top. The only way to get it to puke would be wet sump, add oil, then wet-sump again, and add more, then maybe after the sump empties it would be full enough to come out the top. But that's because there's way too much in the system. This new "venting problem" would NOT have started due to a venting problem. To say that is mis-diagnosis (which I'm sure some have made that mistake).

To quote from aswracing post linked above "Excessive airflow & oil discharge through the breathers can be caused by malfunctioning umbrella valves that are allowing air into the motor." I think this would apply to any venting mod with an inadequate check valve. A regular PCV valve doesn't work well enough as a check valve.

Agreed, the extra air intake is harder on piston downstroke.
But why is it even harder when the oil is hot?
Operating temps give clues to conditions that end up being bad for the engine.

By air compressor, I mean UNDER the pistons. What happens at the intake & combustion chamber, stays there (mostly).

Hot oil is a symptom, not a cause. It's confusing because bike also runs different when oil is hot - but that's not relevant, just need to find what made it hot.

The oil gets hot because of a)hot weather, slow traffic + high revs; b) lean running conditions; c) wet-sumping.
Any of these are easy to detect.
Venting = not a factor


There is a balance I'm looking for that has to be maintained.
I need data for a more complete understanding.

Don't need more data, already confused. Just need to compile it. Keep it as separate topics, even if one can cause the other:
-Wet-sumping
-CC venting



bustert 22nd July 2019 16:45

while that is true, that the air cleaner MUST flow more than the cfm of the engine needs, the media does in fact effect air flow. of more importance is how or the direction the flow must take. the best is a direct inline flow which does not happen with an hd ham can. if you introduce angles, they must be wide radius and the ducting of correct size as every curve or turn adds resistance and more importantly turbulence, best to have laminar flow.
my vents are not stock and probably flow more.
when the the vent exists the orifice, as mr. hippy mentioned, the velocity must increase but after the orifice the pressure must drop and drops greater as distance increases. when this vent hits the volume of the can, it becomes lazy and more so with little throttle demands at idle. now what happens when you get lazy flow, well anything in suspension will coalesce and drop out. this leads to oily/water mix. now is the really a vent issue, hummmm, well maybe and maybe not, i am more inclined to believe it is an engine condition issue since it progresses with age.
as an example, ever fooled with pontiac engines with trip-duce?
really could be anything but this is a personal example.
if the carbs are syn to open in one felled swoop, on a take off, the air flow becomes near atmospheric for a brief moment, the fuel drops to the manifold floor, this results in the two inside cyls on both banks to run rich and the further cyls to run lean. an ole trick was to groove the manifold floor so that any drop out was directed to the leaner cyls.

Hippysmack 22nd July 2019 16:54

Quote:

Originally Posted by aswracing (Post 5310625)

First, a little background. In the stock configuration, the crankcase vents through a pair of "umbrella" valves, which are essentially check valves. There is no air inlet into the motor. As I understand it, the idea is that as the pistons come down the first time and the crankcase air is expelled, the air is forced out through the umbrella valves. But when the pistons go back up, the umbrella valves block the inflow of air, causing a slight vacuum in the crankcase. The next time the pistons come down, crankcase pressure will return to atmospheric. If no air is allowed into the motor, the crankcase will cycle between a vacuum (pistons up) and atmospheric (pistons down).

I read that post, not the whole thread yet, but:

I agree as I mentioned earlier, that the crankcase is at atmosphere while not running.
And a slight vacuum is pulled while running.
Then a push - pull is established while running.

But 'the next time the pistons come down, crankcase pressure will return to atmospheric."
Inbetween that you get this:
The first thing that happens on downstroke is that positive pressure (greater than atmosphere) is generated due to the restrictions of:
Case volume
Path to the vents
Vent hole size
Vent line (if applicable) length
Any induced air from the breather valve(s) not closing properly

These things will bring the pressure inside to higher than atmosphere, else there would be nothing to expell.
As the air is pushed out of the vent, at BDC, the air returns to atmosheric. Check.
That is the problematic condition, the higher pressure before returning to atmosphere.

The negative (vacuum) on upstroke I'd think is more stable than the positive pressure on downstroke due to ring blowby and others.
But ring blowby can also happen during upstroke depending on ring condition, thus oil entering the chambers.
Blowby adds to positive pressure which throws out the balance.
Let's use X (+1) as positve and Y (-1) as negative.
In a pefect world, X goes down and Y comes up ------ X+Y=0
Add ring blowby and you get ------ X+1>Y------ or the real result. Balance is off by nature of the moving parts.
The pistons move up and down almost together.
That makes the push/pull environment more violent.
Add a vacuum pump with Z (-1) amount of pull:
Now you get X+1=Y-Z... seems the balance (to zero) is restored even though positive pressure is compiled of blowby.
But the lower the negative pressure is at the beginning of the downstroke, the lower the positive pressure will be.
If you are generating 2 psi of positive pressure on downstroke but reduce it's beginning surge to -1 psi (Z), the result will be only 1 psi of positive pressure during downstroke.
-1 (+) + 2 equals +1.
The more the vacuum, even lower the positive will begin.
The rings act as a buffer between these two conditons as excess pressure could run both directions.
But positive pressure aides in oil scavenging.
So lowering positive pressure by default also hinders scavenging.
That's why racers with vacuum pumps use multistage scavenge pumps to account for the imbalance to scavenge and improve it.

Same thing with lowering the oil level in the tank.
You are lowering the amount to be scavenged later which lowers the amount of oil that could get suspended to mist thus lowering the density of what does get suspended.
Lower density of suspended oil drags the wheels less being lighter as it moves.

I've read posts where there was a concern with the plastic tank neck warping which would change the seal condtion of the O-ring.
If you do test your oil tank pressure, could you take pics of the apparatus ?
That'd be helpful to others I'd think.
More data is needed in the form of testing data.
If you pull a vacuum on the tank with a mighty vac to test it, how much vacuum or how much is too much will it take to do a proper test?
That depends on what the engine would pull at max volume... which is ?? volume.

I'm broke right now but I want to do some flow testing on the breathing system when I can so I can examine real data instead of figures out my arse.

All tanks no matter of construction have puked oil from higher pressure with the cap on just like the breathers puke oil.
The oil level isn't getting higher but the pressure above it is.
This causes the pressure to break the seal of the cap or bust the tank and bring oil with it from below.
With the cap off, the pressure is relieved.

Also with the cap off, you are connecting the entire pressure system including the crankcase and rocker boxes to atmosphere.
As far as air pressure is concerned, they are all as one.
You can't have more pressure in the rocker boxes than what's in the cam chest or crankcase.
The air has to back up from the source first and then reciprocate throughout the system.
That is why pulling the cap matters, the air throughout the bottom end including the top will react to the cap being off.

As cause and affect, if the tank is leaking, why wouldn't you also look into the breathing system?
Same as weeping rocker box gaskets. Why wouldn't you add the breathing system into diagnosis with bad gaskets.
I think it's the big picture not being diagnosed is what I'm getting at.
Hence, I agree with carrying on to other tests.

Too hot oil is a symptom but it can also cause other problems as in less residual lubrication and damage thereof to pistons, lifters, bearings etc.
As I mentioned, it can also cause more oil to be suspended, drag the wheels (less power), overpower the breathers (oil puking) etc.
Sometimes it's not as easily detectable before it does damage to an extent either.
I do have these as separate articles in the Sportsterpedia but have brought wetsumping into the CC pressure article as it relates.


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