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

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).


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