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

Hippysmack 1st August 2019 22:05

Damn, I could have won a million bucks if you'd given me 5 more minutes to bet you'd say that. :laugh

I'm offering, not condoning. :p

needspeed 1st August 2019 22:24

I haven't paid much attention to this thread, but while reading some of the later pages I noticed post # 352. It's fantastic. Forget about doing a search. Anyone wanting to read about this subject could just start with this post.

It must have been alot of work and taken a long time to compile that list of links.

Thanks Hippysmack. Well done.

Hippysmack 1st August 2019 22:28

Quote:

Originally Posted by needspeed (Post 5767037)
I haven't paid much attention to this thread, but while reading some of the later pages I noticed post # 352. It's fantastic. Forget about doing a search. Anyone wanting to read about this subject could just start with this post.

It must have been alot of work and taken a long time to compile that list of links.

Thanks Hippysmack. Well done.

Nothing but a labor of love. :)

edit:
I went back and added a link to post #352 in post #2 for posterity. :geek
edit again.
Credits were moved to post #335.. so far.

60Gunner 1st August 2019 23:28

So this mounts in the cover? Not quite sure how it would keep any splash from my fitting. Just pulled the fitting and it as well The 7 inches of hose to the krankvent are pretty much clean. What does come out is pretty thin and blows right thru to the end of the exit hose pretty easily and quickly from what i can tell. No gunk buildup inside of the hose or fitting at all.

Hippysmack 2nd August 2019 01:37

Yep.
It's all internal.
The baffle tube houses the umbrella and the drain hole for separated oil is inside the molded cup in the cam cover (drains back to the cam case).
The vent line exits about 11:00 of the cover (OEM line goes to A/C).
I've heard it was some fine engineering. :rolleyes:

Good to hear it's not mayonnaise again.

60Gunner 2nd August 2019 03:28

So would the vent line be able to hook to the fitting inside where mine is located?

Some of it sits in the krankvent and exit hose and does thicken as it cools.
I plugged the cam cover with a short piece of hose clamped to bolt and ran it off the heads with no hose after the krankvent so as to see any dripping. I didn't ride far but did get on it and not a drop came out. I'm sure the stock breather assemblies have a part in that.
Filtering out the oil before it leaves the cam chest would be similar and a huge plus for venting there.

dieselvette 2nd August 2019 04:20

Quote:

Originally Posted by Hippysmack (Post 5766608)
Thinking out loud and may be full of it.
Mine lopes like Hell on startup.
Oil is thicker, no oil in the cup to drain from that little hole and air is pulled thru it.
Bunny says you get no measureable (extra) blowby on startup.
But that pesky hole...
Progressively, as oil heats up, it fills the cup, no air pulling in the hole.
Idle levels.

You could prove it by using your fingers to plug the breathers immediately after startup, if you do feel pressure maybe let it out, but don't let ANY in. Not totally fair if you happen to trap some pressure in, but at least you rule out the reverse flow through drain hole.

My belief is that the hole is not significant, with or without oil there. If it was designed to need an "oil supply" to slow down air-IN, the "balance" would be exponentially harder (read: impossible) to maintain.

However - without the restricted breather bolt, the oil drain hole becomes a lot more significant. Only because this flow is pulsing. But maybe not enough to matter on a stock bike.

dieselvette 2nd August 2019 04:21

Quote:

Originally Posted by Hippysmack (Post 5766675)
If these areas allow air to be pulled in the engine on upstroke, the added air will compound any other existing breathing problems.

It could, but in theory it takes a more substantial leak (or many small leaks) to be significant. (It would at least weep oil?) I say that one should fix ALL oil leaks, because I don't want the average Joe to question if the leak is "bad enough" to affect venting.

dieselvette 2nd August 2019 04:25

2 Attachment(s)
Quote:

Originally Posted by 60Gunner (Post 5766914)
You're not running a vacuum with breathers that allow air back in and restrict it going out. Most oil mist will get sucked into the intake. If your rings are shot that excessive blowby is going somewhere.
Probably have leaky valve guide seals too allowing the the crankcase pressure to push blowby past and into the combustion chamber if those are stock. A known issue if yours were never replaced. Something I also replaced when I did this build because mine were leaking.
Your poor ring seal would also lend to crankcase pressure not vacuum.

Looking at my valves and under the heads, I think you are right on all accounts.

Except I believe my breathers were working fine, because on the bench they behave *almost* exactly like new, and I never had oil puking. Final answer is TBD if I ever get my heads back from the indy..........

Perhaps off-topic - look at these pictures of my valve covers. This is after wiping down, but no other cleaning. Everything inside the engine looks like clean & new - as in no varnish or darkness anywhere. Except the valve covers my theory is that hot combustion gasses were "burning" oil onto the surface. It is most significant above the rear exhaust valve. Or is this normal?

dieselvette 2nd August 2019 04:28

5 Attachment(s)
Quote:

Originally Posted by dieselvette (Post 5766866)
My stock setup never had oil come out the breathers ... nary a trace of oil in the a/c.

I need to rephrase, but only slightly - there may be a "trace". The intake is 100% clean and dry. This has not been touched with intake cleaner or any sort of anything for over 60,000 miles. It's bone dry and looks like brand new inside. (No pics of the carb, but it looks the same).

The breather tubes I tried to swab in there and get oil out. That's where I found a traces - but no accumulation, only a film if anything. Same with the breather bolts.


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