[tooseevee]

The original breather system was a 11 inch piece of hose with a duckbill on the end.  Exited right over the sprocket and chain.
Piston came down duckbill opened and vapor came out, piston goes up duckbill closes and creates vacuum in case. System worked flawlessly for 40 years before they started exporting them to the sensitive country's.
Very little oil vapor comes out of mine and what does lubes my chain for me.
What I have noticed is if I fill the oil tank up to the max line in the dipstick it will spit oil out until it gets down to about the halfway mark and then it stops and stays pretty much there. So When I add oil I only go up to the halfway mark and leave it at that. That has been a common thing on the 3 iron bbls I have owned and a friends AVL.
CJ

            That's exactly what I find on the '08 AVL. Many years ago I sealed the timing case opening, ran the other hose up and over and into a used DryGas container (painted black) with the original duck bill on the end of the hose. It fits perfectly down in between the downtube and the rear fender. I keep the oil level no more than half way up the cross hatching on the dipstick. Like you I found out early on that if it's higher, the engine will spit it out to the level it's sposta be.

            Also on an AVL, don't check the oil after the engine has been off overnight. The dipstick will show you have ZERO oil. Not true.

[ace.cafe]

That precisely what I have in mind.  Perhaps the opening I have drilled is way too large.  To make things worse I have later enlarged its diameter (see photo).  Result was such that after starting the engine i a matter of just a few seconds the side of the engine was dripping with oil.  Maybe installing some restrictor of i.e. 2mm (or less) diameter would help.  I did not try it yet.  As an alternative I am considering adopting a solution similar to one that is used in my Harley Evo engine.

7mm - 8mm is about right.
There must be a breather hose attached to it, and it should be routed up high on the frame(as noted by others) to a air/oil separater can with an internal duckbill valve(like the factory catch can system), or to a duckbill or one-way valve like a KrankVent, and then a suitably routed exit vent hose. Or, you could use the old factory duckbill alone, such as T120Bullet describes.

The crankcase breather elbow should not be just left open without a hose and one-way valve. It would blow out a lot of oil if left open like that.

[Bilgemaster]

Just to add my two cents to Ace's advice, for your ready reference the doodad that cured my Bullet's "Oil Sploodges" was this KrankVent knockoff sold on eBay by Panic Cycles in Richardson, Texas for $34.95. The name brand Hayden KrankVents run north of 100 bucks.

I am quite sure there must be many  other, quite possibly cheaper, options out there on the shelves in the way of PCV or duckbill valves that'd work, but that's the one that did the trick for my Bullet, and she's been "Sploodge-Free" for nearly two years now. The part itself is very well made for a knockoff, and is even serviceable, coming with an extra replacement rubber doodad. You just unscrew the vent, and pop in the new rubber.

[tooseevee]

Just to add my two cents to Ace's advice, for your ready reference the doodad that cured my Bullet's "Oil Sploodges" was this KrankVent knockoff sold on eBay by Panic Cycles in Richardson, Texas for $34.95. The name brand Hayden KrankVents run north of 100 bucks.

I am quite sure there must be many  other, quite possibly cheaper, options out there on the shelves in the way of PCV or duckbill valves that'd work, but that's the one that did the trick for my Bullet, and she's been "Sploodge-Free" for nearly two years now. The part itself is very well made for a knockoff, and is even serviceable, coming with an extra replacement rubber doodad. You just unscrew the vent, and pop in the new rubber.

            You're right, of course, that there are many of these little valves out there and some of them are ridiculously expensive. I believe that splooges as you call them are not caused by what's on the end of the hose, but are caused by an over-filled crankcase and not so much what's on the end of the vent hose.

             I still use the original duckbill that came with my '08 AVL, the same one the cavemen used, and run into a repurposed plastic DryGas container painted black and tucked in between the downtube and the rear fender where it is just about unnoticeable and I have no splooges or any other problems with it. The only thing that's ever in the "catchcan" is a few drops of foam condensation from when the oil is still cold after that first cold start of the day.

             These engines will get even with you from being overfilled by blowing the excess all over the place until the oil level is correct.     

[Bilgemaster]

            You're right, of course, that there are many of these little valves out there and some of them are ridiculously expensive. I believe that splooges as you call them are not caused by what's on the end of the hose, but are caused by an over-filled crankcase and not so much what's on the end of the vent hose.

             I still use the original duckbill that came with my '08 AVL, the same one the cavemen used, and run into a repurposed plastic DryGas container painted black and tucked in between the downtube and the rear fender where it is just about unnoticeable and I have no splooges or any other problems with it. The only thing that's ever in the "catchcan" is a few drops of foam condensation from when the oil is still cold after that first cold start of the day.

             These engines will get even with you from being overfilled by blowing the excess all over the place until the oil level is correct.     

Nah, I didn't overfill it with oil. In the post-mortem it turned out that the return line from the canister to the inner side of the timing case was clogged with a thick brownish mayonnaise-like substance. Unable to flow back into the crankcase via the timing case, the oily vapors just kept condensing and gathering in the catch can until they reached the higher level of the port in the can that had previously been connected with the inner side of the air filter box. This had been disconnected by a previous owner, presumably after having fouled the air filter, and a longer hose run instead from the catch can down to near the centerstand. That was the exit point, the urethra, if you will, of the sploodge. It probably didn't help any that the little rubber duckybill check valve within the catch can seemed upon examination to be in a state of perpetual astonishment, locked in an eternal "OOOOO!" Clearly it had given up on "checking" anything. In retrospect, I could have cleaned out that clogged return line and the others with some spray carb cleaner or something, replaced the worn out duckbill valve in the catchcan, and been back on the road "sploodge-free" for a time, but I'm glad I took the simpler longterm KrankVent route.

[ddavidv]

Mine has the duckbill. It works a treat though certainly has no shortage of oil for the chain...and everything around it the chain can fling it onto. A quick wipe with a towel after a ride and all is like new again.

[ace.cafe]

There will always be at least a little bit of oil mist that comes out. There shouldn't be a lot.

[Tarnand]

This is what I have done for now - the oil pipe goes to the oil separator with a duckbill in it.  Until now I was totally not aware about sensitivity of the oil level.  We will see how it goes.

[tooseevee]

This is what I have done for now - the oil pipe goes to the oil separator with a duckbill in it.  Until now I was totally not aware about sensitivity of the oil level.  We will see how it goes.

             Your seat setup is perfect. I have the same seat in black and had it like yours in the beginning (had the Lycette seat before). With the springs it was still too high (I can't do the tip-toe thing, I need the extra control).

              So my seat is flat on the frame now (yes, it's fine. I'm used to hardtails) and brings the ground up to where I can 99% flat-foot it.

              I love the look of the ironhead without that huge lump of starter the AVL has stuck onto it 

[Adrian II]

tooseevee, owners of AVL500s can perform a lumpectomy...

A.

[Bilgemaster]

Maybe I'm wrong, but I would be a little concerned how that breather pipe dips just after the crankcase outlet. It just seems to me like a big long welcome mat for "cloggery". Although my bike's breather hose runs from off of the existing later-style outlet on the inboard side of the timing case, I did my best to give it an immediate high curved slope of maybe 45 degrees from there to my new KrankVent, which was simply tucked in high behind the battery, with a long hose from it down to near the center stand.

If yours should still experience oil loss problems or clogging, then in your case, coming off the left-hand side of the crankcase, I might suggest mounting some suitable 90 degree elbow at the crankcase outlet pointing towards yet clearing the cylinder barrel and perhaps slightly upward with a flexible hose attached there and running rearward and over, or perhaps resting on, the housing behind the ignition cap at an upward incline and rearward.

Then again, who am I? Archimedes? One of the Mario Brothers? Like I said, I could be wrong and may well have completely misunderstood the principles behind the whole crankcase breather system. So, if your bike runs fine henceforth, kindly disregard.

[tooseevee]

tooseevee, owners of AVL500s can perform a lumpectomy...

A.

            No, Adrian. I have tweaked this '08 bike enough. When you can't even get your clothes on (or off) (or do ANYthing) without pain you just have to stop somewhere and say "Enough. This is the way it stays".

[tooseevee]

Although my bike's breather hose runs from off of the existing later-style outlet on the inboard side of the timing case,

           

           I'd like a picture of how your engine is hosed. Because if the picture I'm getting in my head is correct, that's not where a breather hose should be.
 

[Bilgemaster]

           

           I'd like a picture of how your engine is hosed. Because if the picture I'm getting in my head is correct, that's not where a breather hose should be.
 

Too dark and too damned cold for photos. But, I think many would agree that "not where a breather hose should be"  is the operative phrase here, since it arguably shouldn't be where it is on mine at all. You see, in the final model variants of the Iron Barrels and later their successor AVL engines, the breather outlet was moved from the left-hand of the crankcase, where both The Lord and Redditch intended, to the inboard side of the timing case, with a second inlet port placed nearby as well. The outlet hose was routed to the bottom of a kind of catch can canister, within which was affixed an upward-pointing duck bill type check valve (kind of like a whoopee cushion valve). Just a bit higher up on the catch can, coming off the side, was an outlet that connected to a hose than ran back down to the aforementioned inlet port. This was to allow any condensate to flow back into the crankcase via the inboard side of the timing case. Still higher up in the catch can canister was yet another outlet on its side connected to a hose that ran into the inboard side of the air filter housing. This was to recirculate the vapors from the breather back through the carburetor and into the combustion chamber. The whole rigamarole was a last ditch slapdash effort intended to reduce emissions in this aged engine design. The problem is that if the return hose clogs or the little duckbill valve goes bad, both of which are likely after a time, then the whole goofy catch can affair overfills and begins spewing oil into the air filter, fouling it. A previous owner, presumably afflicted by this, had removed the hose on mine from the catch can to the air filter housing, and ran a longer one down from the can to near the center stand instead, just dangling there open to the ground. This is where on occasion most of the contents of my oil tank would suddenly sploodge out onto the ground below the bike. Replacing the catch can system with a simple hose sloped upward from the breather outlet to a KrankVent type check valve tucked high up behind the battery, with a hose from it down towards the ground cured mine about 10,000 miles ago. I just capped off the old inlet ports on the timing and air filter cases with wine corks. It's been sploodge-free ever since.

If you really need some pix, lemme know. Maybe tomorrow...

[Tarnand]

[...] Like I said, I could be wrong and may well have completely misunderstood the principles behind the whole crankcase breather system. So, if your bike runs fine henceforth, kindly disregard.

The bike runs fine, however, as I previously mentioned I was completely oblivious to how the oil level in the tank influences working of the breather system.  How actually it is going to work I will not find out until spring. 

My original idea for modification was to vent the crakcase through the cylinder head, just as it happens in my HD.  In order to do that I need to drill a small hole (2mm ?) between crankcase and the tappet chamber.  From the crankcase side the hole would be baffled by the bore liner.  Oil mist while being forced from the crankcase would be hitting the intake pushrod catching some of the oil droplets.   Next it would travel to the intake rocker chamber  and through a rubber hose with a checkvalve on its end then to the outside.  During this route some more oil droplets would settle on internal engine parts.   If it does not work these holes could be plugged with no problem.