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

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.

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.

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.

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.

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.

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.

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?

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.

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).

+1!

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

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.

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.

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.

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.

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.

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.


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'.

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

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.


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.

I didn't assume anything. He said his rings were shot. If that's the case and the blowby isn't coming out the breather bolts, it's a fairly educated guess it's being blown past bad guide seals since they were defective in the first place and he's never replaced them. He's more or less confirmed this by the carbon build up in the combustion chamber.

The size of the hole in the bolts can make that much of a difference. I'd be willing to bet just as many are running aftermarket bolts with the bigger holes than are running the stock ones since the first thing people do is get better ACs and vent externally. I haven't seen aftermarket bolts with small holes. I could be wrong.

If my oil wasn't getting to the pump, it would be pumping my tank full of bubbles. Which isvwhat was happening with too much pressure and oil not returning. Evident by my leaks. The krankvent stops these leaks by maintaining a constant pressure or slight vacuum and thats a claim I do buy. Too many claims of leaks disappearing to not buy it.
Whether it be slight pressure or slight vacuum, I think it does a much better job at maintaining a constant. Too much up and down with the pressure with the stock breathers for whatever reason and it's just not necessary. That's my theory anyway.

You're right to an extent. Tho there are a few places in the intake port that would be better opened up. Wedge sent me diagrams detailing this and what he did as I intend to do a little home porting this winter.
But yes, intake rough for the turbulence(Not intake manifold tho), exhaust smooth.

There's a fair amount of oil but you're right about it not being flung around. My breather gauze was saturated but then I'm not sure how much excess oil was sitting in mine due the excessive crankcase pressure.

My apology's, I must have missed that somewhere.
I am having trouble getting away at the moment.
But I fired mine up and got the oil temp to about 140F, pulled the cap and the engine died.
Fired it up with the cap off and it would idle, just a little rough.
So it's not the fact of the cap being off that kills the engine.
It's a sudden pulling of the cap that does.

I also watched inside for froth with the cap off.
At idle, a thin layer forms on top of the oil.
Pulled the throttle to 3000 RPM and the froth disappeared.
Back to idle, the froth came back.

I tried to get a short video with my camera but that didn't work out.

I go the other way on where to site it as I prefer the breather to be near the pistons to be able cap the considerable pressure
pulses on an engine that has one crankpin. Hence I suspect a head breather will maintain a higher average CC pressure if
all els se is equal and both systems have fresh umbrella valves. The other down point is the heat which we seem accept ages
the elastomer umbrella valve in the heads. The two points in its favour might be less oil mist in the rockers but that is why crankcase
mounted breather have oil baffles and less visible hoses.

Oh dear, that sounds serious Hippysmack:sofa

Hahaha..
I'm just analyzing, not worried.
I didn't have it to operating temp either.

edit:
I tested pulling the oil cap back to back with the A/C off and then on.
Keep in mind, the oil cap off is allowing CC pressure to escape and atmosphere to enter the engine.
A/C on, I get lower RPM and light froth only at idle.
A/C off, I get no response difference I could notice but bubbles and froth at idle.
I may be goosing the throttle too much to get the temps up though.

I'll add, the froth is Not raising oil temp as I have yet to get the temps over 140F.
(big fan on the motor)

Have you done a compression or cylinder leakdown test lately?

Did both about a month ago.
Didn't write the results down (need to start doing that) but they were both good.
Actually I wrote them on a piece of cardboard and can't find it. :o

You might be getting crankcase pressure/oil past you guides too.

On 2nd thought, what carb are you running? And aren't you venting to the AC?

I think he is venting to AC - and thats why I think the test with/without AC is telling - In normal setup the small amount of gas out the breathers into the carb is enough to affect the tuning, and then pull the oil cap and the crappy air comes out the oil tank, instead of the breathers? So Hippy says without the AC then the oil cap has no effect, just thinking that confirms my suspicion, but I could be missing something.

I had my pipes off recently, valves looked fine.
Gotta start writing dates down...
No oil buildup or residue, just light carbon.
I do not have valve guide / seal problems.
I'm not using oil.
Bike runs great, no wet sumping, no oil puking.
Undoubtedly, I'm not having excess CC pressure buildup either.
I thought I'd already established that.

edit: I'm just seeing how it ticks. :)

I'm running a CV and currently venting to A/C.
I recently pulled the carb to adjust the float.
I just pulled it again today (dated now ;)) and blew out everything.
No passages blocked.

I noticed this morning while partially blocking the breather vents with my fingers,
At idle, the vents are puffing outward.
On throttle, they do not and seem to pull a slight vacuum.

What I'm getting at here is why the bike stumbles upon oil cap removal, but with the AC removed it does not. (Or did I misunderstand earlier?)

Any gasses that would normally go in the intake, your bike is tuned to accept and run great in spite of those gasses (no matter how minimal). But when you remove the oil cap, the gasses take a different path (out the tank).

So temporarily venting the gasses from the breathers to atmosphere (by removing the AC) is that why you get different results with the oil cap test?

As a side note, I'm really surprised it makes such a difference, and so the questions earlier about engine condition.

That's correct.
Oil cap off, A/C off, no stumble.

I put the oil cap back on with the A/C off, engine running.
Then installed the A/C.
The RPM didn't change while doing this (going from not sucking CC pressure to sucking CC pressure).
No harmonic change either.
So I wouldn't think the tuning changed much if any.

Well everything I've read says the the extra unmetered air but that's on cars.
Maybe your breathing is to restricted going into the carb and isnt getting rid of the excess crankcase pressure intoduced thru the vent line from the tank to the cam chest.
Either that or I was thinking something along the lines of the vacuum operated slide being affected.
Venting to atmosphere it doesn't happen.

I, too, like the idea of having the crankcase breather coming out of the cam cover as 60gunner and others have done. I'm thinking of something like this, https://www.metcomotorsports.com/pro...p?prod=MBR0009 , at the 12 o'clock position with the idea the oil drains back into the cam cover.

Two things and I don't think they relate.

First, with the CC pressure puffing at idle and not puffing with throttle,
Running down the road, I'm not pumping into the A/C.
I basically recreated the balloon in my head as I tested with my fingers.
How can it run right if CC pressure is part of the metering (when not pumping into it on a ride)?
I got throttle I ain't used yet... well a little...
105 with some left so far, no sumping, no puking.... no cops. :D

Second, it was quick to froth with the oil cap off at idle (but not with throttle).
Froth is aeration.
There was a ton of time for the sump to empty after startup.
I don't think tuning changed my CC pressure.
I did use some on/off throttle that may not have helped.
Drain hole in the breather cavity not filtering oil that isn't traveling there but the toward the oil cap thus pulling in more air?

I'm having a hard time with the A/C being off in the picture. :doh

edit:
I did check the slide circuit and all seems good.
The carb pulls it's air thru the filter which is way more than what the breathers can deliver... and only at idle, or high revs.

You're thinking of manifold pressure, but that's behind the carb.

When I say "tuning" I guess is confusing. It's not about pressure or flow from the breathers, but the fact that it's hot air with no oxygen, and possibly oil vapors. That results in a different mixture than with 100% fresh air. At idle this makes up a percentage of the total intake air. But, if the bike is tuned to idle on this shi++y air then OK you don't know the difference until the vents are moved (or oil cap removed).

The more you open the throttle, the less impact this stale air will have on your mixture as it becomes a smaller % of total air. (But, it still has an impact on performance).

PCVs made for autos seems to be frowned on although many are apparently using them.
The check valve should be in the bottom on that one.
For $60 hope it works (may be a spring / check ball they don't say).
I'd like to see a reed valve on a cam chest mod.

Post the results and pics when you've got it done. :)

Not entirely. The CC vent to tank is 1/4" hose and what 2ft long? The air doesn't just turn around and flow backwards that easily. Which is why having say, an open-ended 6ft length of hose would be as good as any umbrella valve in many scenarios.

Think of a tuned exhaust and cam overlap - exhaust valve is still open after exhaust stroke, while piston is on the way down, yet the air continues to flow out the exhaust valve because of velocity. By the time air starts to slow down the next pressure wave is there to keep it moving.