The Sportster and Buell Motorcycle Forum - The XLFORUM® - Sportster Crankcase Pressure / Engine Breathing / Wetsumping and Mods

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

This air cleaner has at least 30,000 miles on it. Inside of it the metal part, if you wipe your finger, it feels sort of slippery which is probably buildup due to oil vapors mixed with rainwater. But its not much - I would describe it as enough to dirty up your eyeglasses, still you could see through them fine.

The brown-looking marks are probably from rainwater swirling around in there as I've been riding without the cover over it. Brown probably from fine fine dust sticking to water droplets (note that oil when I drain my bike is not brown, it's clear).

Quote:

Originally Posted by four speed (Post 5766981)

as i suggested before, maybe all this needs is a pragmatic approach: If you get excess oil mist down your leg, gaskets that are oil misting
or notice that the oil tank is filled with foam, try renewing the stock umbrella valves (not easy on an the 86-90 engine due to availiability)
or replace them with a proprietary valve and see if it helps.

+1!

Quote:

Originally Posted by 60Gunner (Post 5767050)

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.

This is too short-term. You need to ride for 100's or 1000's of miles and then see what you get.

Quote:

Originally Posted by Four Speed (Post 5766983)

In practice I find very little oil comes out of the camchest breather, mostly water vapour. The stock 86-90 set up has an effective oil baffle and combined with a decent one way valve the oil mist should be minimal.

What were the IH's like? On my 1980 IH I don't remember ever having oil from the breather. At the time I didn't even know what a breather was. But I'm dang sure if there was oil dripping I would have fixed it.

Quote:

Originally Posted by dieselvette (Post 5767077)

This is too short-term. You need to ride for 100's or 1000's of miles and then see what you get.

No you don't. One good hard run will tell you.

You really need to vent somewhere externally and not in your AC. That point is not even debatable. It's just bad.

Quote:

Originally Posted by 60Gunner (Post 5767082)

You really need to vent somewhere externally and not in your AC. That point is not even debatable. It's just bad.

I totally agree, just never cared. Until now. So along with my top end refresh, I'm going to re-direct the stock hose thingies each to a hole out the back of the A/C. And then hope that never enough oil comes out to make a mess.

Take it out and down between the cylinders at the bottom to the other side then back and down under the starter to come out just in front of where the rear brake line starts to go up. Anything that might come out wont end up all over the bike or the rear wheel there.
That's what I just did with the krankvent just now testing it off the heads only off horseshoe breather hoses behind the AC not in it. Practically hidden that way too. Just enough room to get a 5/16 hose thru the bottom of the cylinders.

Quote:

Originally Posted by 60Gunner (Post 5767062)

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

I'd imagine you'd have to tap the inside of your 90 deg bend and screw in an extension to bring that line into the cover.
And brass fittings ain't that trustworthy.
So extending the line farther inside is probably not good.
I first envisioned a circle welded behind your baffle with a hole drilled thru to the front with offset holes.
But that does add weight to the assembly.
And air/oil can travel thru the case side and bypass the baffle anyway.
But you have the rocker box drain coming in there so it couldn't be too wide.
You wouldn't want to arrange for that oil to be easily routed to your baffle.
Truthfully, you can't seal it to the cover so I guess you could get more elaborate but I'm not sure it'd help much.

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.

You can't assume the engine had ring problems, valve guide problems and shot breathers. :frownthre
These are diagnostics that must be done first.
The OEM goal was not to pull anything over a slight vacuum.
Look at the balloon again.
More vacuum equals less scavenging.
I know you have the new pump, but if the oil is not pushed to the scavenge hole, your new pump is useless.

Quote:

Originally Posted by dieselvette (Post 5767070)

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.

My 98 has the OEM bigger breather bolt holes.
I'd need to plug them when hot to see any difference since I don't have a problem on startup.
It's when it heats up is when it starts.
I haven't had opportunity to look into it yet.
Maybe I can today.

Quote:

Originally Posted by dieselvette (Post 5767071)

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.

As we've seen with the small breather bolt hole, it doesn't take much to manipulate CC pressure.
It would most likely weep and then pull in air which would manipulate the pressure.
But not necessarily screw it up unless there was also a problem with worn breathers 'on the brink'.

Quote:

Originally Posted by dieselvette (Post 5767073)

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?

It does look like had more heat around the valve area of the covers.
Looking at the top of the heads, the chamber where the valves sit is separate from the other side of the covers.
So it may just be normal. Others may have a better opinion.
http://sportsterpedia.com/lib/exe/fe...pysmack_6_.jpg

Quote:

Originally Posted by dieselvette (Post 5767074)

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.

That's what I meant earlier, there will always be a trace due to the nature of what's coming out... very fine mist.
You may not see it as it comes out but it is there.

edit: You can port the inside of the intake, I've done mine and others have also.
That might help keep that from forming.
There is, of course, a debate about that too.
Whether it helps or hinders gas flow.

Quote:

Originally Posted by dieselvette (Post 5767078)

80 model had a round reed valve assembly mounted in the same spot as the baffle tube pics I just posted.

if the evo is anything like the iron, porting the short intake makes little of anything and it has been said that the rough surface helps with gas mix. the exh makes more sense.
if you ever run an iron with the breather miss timed, there will be a notable diff as rpm goes up, pretty sure the evo will respond like/kind.