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[GreenMachine]

I never seen that much mayo either...has he been riding it in the rain or blasted it with a pressure hose.....

[Geirskogul]

No rain, and no washing.  It was just that once, though.  Now it's just a fine oil mist coming out of the duckbill (after a few more rides today). 

[PhilJ]

No rain, and no washing.  It was just that once, though.  Now it's just a fine oil mist coming out of the duckbill (after a few more rides today). 

Geirskogul, my '08 AVL acted similar to yours when I tried using the vent out to the rear, like you and many others. I quit that because too much oil was puddling at the ass end.

My solution was to keep the catch can, but modify it's function. I turned the crank vent around as has become common practice, then ran the output of the catch can out the side, placing a plug in the hose. Then I could check after a ride or on the ride. What I found was that I had very little oil collecting in the catch can now. I only check monthly.

Vince had once cautioned about long vent hoses. I know some use them with success. Mine seemed to act like a syphon.

[Geirskogul]

Okay, see, I've been riding around town all freakin day and, besides a little teeny puddle out of the breather after a long stop, I've experience no measurable oil loss.  It's even overfilled by quite a bit (1-2cm on dipstick when screwed in) and it's not blowing out or burning at any measurable rate.  It still "waves" up the breather hose after it warms up, but it always drains back down.

Maybe it's the higher speeds?  Maybe I should add a makeshift "catchcan" (ie: bulged container in-line vertically with the breather hose) to let  oils collect at higher RPMS and drain back down at lower RPMS?

[ace.cafe]

This might seem like an obtuse question, but I notice that you have a hose connecting the timing chest to the primary chaincase.

I'm just wondering if it's also blowing oil into the primary chaincase, as well as out the breather?
If you check the oil level in your primary chaincase, and it's way over-full, then maybe it's blowing the oil into there, and it's not all going out the breather.

I'm trying to get a handle on where the pressure build-up is coming from.
If it's coming from the timing chest, you may have a compression leak at the head, causing high pressures in the oil return system.

If that's not the culprit, then you may have ring blow-by.

Basically, this pressure inside the engine, causing oil to blow out, is caused by something, and is not normal to any of the engines that I've seen that were healthy.
So, I think it's a matter of finding what's causing this pressure build-up inside.
The oil isn't just "jumping up" out the tube. Some pressure is pushing it out, and that pressure is coming from somewhere.

[PhilJ]

Ok mine never gurgled like yours with the clear hose to the rear setup. But it did vent more oil than what shows in my modified catch can.

Ace must be getting close on his assessment.

[UncleErnie]

With the timing cover and the primary connected to each other like that, there's really only one vent now.  Right?  Maybe another vent is necessary to equalize pressure or something?   Shooting in the dark here...

I don't like the idea of a big hose venting all the way to the back of a bike because it seems to me that the engine would have to build up a LOT of pressure to push any schmutz UP and out.   It just seems to me like that stuff would just collect somewhere and maybe even block venting? 

[ace.cafe]

With the timing cover and the primary connected to each other like that, there's really only one vent now.  Right?  Maybe another vent is necessary to equalize pressure or something?   Shooting in the dark here...

I don't like the idea of a big hose venting all the way to the back of a bike because it seems to me that the engine would have to build up a LOT of pressure to push any schmutz UP and out.   It just seems to me like that stuff would just collect somewhere and maybe even block venting?  

Ernie,
The purpose of the long tube which goes upwards and then to the back of the bike, is so that any "burps" of oil go partway up the tube, and then run back down into the engine.
The purpose of the breather is to expel the fumes and evaporated water vapor, and not to expel liquid oil.
Sometimes the mayo presents enough resistance because it is congealed, to blow out as globs, and sometimes some liquid follows that by a siphoning action, but it shouldn't be much.
Even if the mayo isreturned into the engine, after the engine heats up sufficiently, the oil and water will separate because of evaporation, and the water vapor will be expelled out the breather, and the oil will stay in the engine. That's why the engine will run clear of mayo, once it is up to normal temps after a long ride.

So, the long tube should have no effects on whether any more or less liquid oil is spewed out. No liquid oil should be spewed out under normal circumstances, except for some mist that is light enough to be carried by the air.

Now, we know that the late model Bullets and AVL models are compromised with a poor breather set-up, so we are not going to get perfection from them. However,we can see that most of these bikes can work sufficiently to not blow major loads of oil out, even if their breathing behavior isn't as good as it should be.
So, we know that they can be made to not spew oil, with some of the mods discussed on this thread. And this bike is exhibiting worse than normal behavior from the breather, so I'm suspecting something is amiss.

[chumma7]

Just watched the video...Woah! I've seen puking oil breather setups before but nothing this drastic. I'm clueless where all the condensation is coming from for that much mayo to develop but I wouldn't bother thinking about it now. The oil loss is what's key.

Check your plug. If it's black and slimey you have a ring problem but I think your rings are fine. Doesn't seem to be anything out of the ordinary coming out of the exhaust in that vid.
I'm with ace, Pull the scavenging pump.. clean/inspect it and test it out. Either it needs replacement or something else is preventing it from pumping oil from the sump.

Your idle is way too high. My gut feeling is you have that idling at 2200-2500rpm. You want to be around 1400-1500 which is more than enough to prevent sprag blowing kickbacks.

[PhilJ]

Geirskogul,

I've been thinking about something you said about checking the oil.  You referred to having the dip stick screwed all the way in. Are you checking it hot or cold. My bike cold, checked like you, gives me zero on the dip stick. The proper way to check oil is after a ride, bike hot or really warm, with the dip stick threads resting against the threads to the oil tank. With that method, some say to run it at half, I run mine at ~ 3/4, after setting for 2-5 minutes. Maybe your overfilled.

[Geirskogul]

I check the oil warm and after a ride.  But I also check it in the morning (I'm very fastidous about parking it at TDC to reduce wet sumping) and If I get no reading at all then I check it with a laser pointer to be sure that SOMETHING is in there before I start it. 

I took another video of startup, shutdown, and another startup when warm just now on my phone; I'll put it online this evening so you can see it moving up and draining.

Which one is the scavenge pump again?  The forward one or the rearward one?  I do get oil flow through the banjo bolts, in a lub-dub-lub kind of way, but I hear somewhere that there's a measurable flow rate I could check for.  I just don't know how much.

[ace.cafe]

I check the oil warm and after a ride.  But I also check it in the morning (I'm very fastidous about parking it at TDC to reduce wet sumping) and If I get no reading at all then I check it with a laser pointer to be sure that SOMETHING is in there before I start it. 

I took another video of startup, shutdown, and another startup when warm just now on my phone; I'll put it online this evening so you can see it moving up and draining.

Which one is the scavenge pump again?  The forward one or the rearward one?  I do get oil flow through the banjo bolts, in a lub-dub-lub kind of way, but I hear somewhere that there's a measurable flow rate I could check for.  I just don't know how much.

If you are getting oil at the banjos, it's pumping, and is probably fine.
Just so you know, the scavenge pump is at the front, and the feed pump is at the rear.

I must confess that I'm at a loss as to what's going on.
Yours is the only one that exhibits this behavior so severely.

I do think it's related to the higher rpms, but I don't know what rpms it's happening at.
You seem to have previously indicated that it's happening above 40mph.
Please verify the speed, and the gear that you're in at that speed.

If you're idling at 2500rpm, which it sounds like you are from that video, that's halfway to redline of the engine at idle. I"m wondering how high you are revving this bike, because you'd be doing 40mph at your idle speed in top gear.

[Geirskogul]

Normally I actually almost "lug" the engine when riding it around.  I've actually lowered the idle since, but I had it a little bit higher because my air screw was badly adjusted and it was the only way I could keep it from dying.  Also it sounds much, much faster than it actually is in that video,  I don't know why.  Maybe it picks up on tappet noise more. 

I'm usually in first until, maybe, 5-8mph
Second gear until, somewhere.  I don't really use second much, except to get to third, trawl around a parking lot, or get around slow corners
Third gear until something like thirty or thirty-five, depending on whether I'm climbing hills or going flat
Fourth gear until 45 or so.  A little higher (maybe) if I'm going up a steep/short hill
Fifth above that.


On the day I lost a lot of oil, I was on a road that had a 45mph speed limit, and was in fifth gear pretty much the entire time.  I was varying my speed between 40 (it's a twisty road) to 55.  All speeds are as indicated.  My speedo is accurate up to 35 then it gets very optimistic very quickly.

[ace.cafe]

Well those are pretty modest rpms, so it's happening in the midrange rpms.

As far as I can tell, it is likely to be something causing pressure to be excessive inside the engine, and those things normally come from ring blow-by or compression leaking.
But, your compression test seems ok.
So, I just don't know what to think at this point.
I've been thinking about this for days now, and it just doesn't seem to add up.

[Geirskogul]

I'll try a compression test at one of those autoschone places tomorrow (they do them for free) to see if theirs matches up with mine.

If you don't mind me asking, what's a dangerous compression range to look for?  Under 100 or so?  My gauge is iffy (read: older than dirt) so it could be reading off or something. 

I bought a bunch of stuff from HD today like brass fittings and more higher-temp vinyl tubing, so I'm going to be making a (maybe temporary) catchcan arrangement with a clear container and do some moderate speed runs to see how much oil accumulates inside it, or if it simply blows out too.

Here's a second video I took during my lunch hour.  Shows me turning it on, off, then on again to show the speed of tube fillup:

http://www.youtube.com/watch?v=ac5CxPI8Uh4