If you run the motor with the rocker covers off you will see that the oil coming up to the rockers creates a fine mist when doing it's job. That misty air gets forced out the breathers. The umbrella valves are good at blocking the bigger oil droplets but you can only do so much. All vehicles are set up like this in one way or another. When I open the intake on my car there is oil in there as well. The pcv valve will block most of it but that misty air gets through and eventually oil builds up. It's just the nature of the beast.

 

Right, but I think what @John Harper is saying is the gas gets vented up and out, but whatever oil in the mist will eventually collect and drip back down into the breathers, eventually getting to the umbrellas, which are supposed to be one-way valves. So over a long enough timeline, more and more oil is going to collect in the breathers and also eventually the hoses. I used to have my hoses routed upwards as well, into a T fitting, then a single hose between the cylinders, back along the left/underside of the tank, and back to the area above the starter, into a catch can, much like @TexasScooterTrash is describing. I checked the hoses at the T fitting at some point, and they had a thick foamy yellow oil residue forming inside them (I'll check if I have a photo of this). Having the hoses routed upwards does indeed separate the gas from the liquid, but the liquid doesn't just drain back into the heads (at least not for me). I decided to switch to just having the hoses route downwards, connect to a barbed T fitting, and into the catch can.

 

I understand how the misty air exits, it's just how the precipitated oil drains back to the system and does not just pool up at the breather bolt outlets. Why do all aftermarket breathers have the hoses go downwards, so any precipitated oil in the hoses drains out, or into a catch can or filter? No one sells one that goes upwards that I am aware of.




In the top picture, there is no drain back hole where the breather bolts exit. The drain hole is above that, near the umbrella valves (picture #2). How does any oil draining back from the external hoses get back up to the drain hole where it can re-enter the oiling system? The oil would have to come all the way up the air breather hole (picture #2) before it could drain into the motor.

John

 

Maybe once a week, more often if I ride especially hard or for a longer period of time. I don't ride daily, but I'll be starting to, and I'm not looking forward to emptying it even more frequently. Not a whole lot of oil comes out, but some does. I forgot to empty it after a couple longer/harder rides, and the catchcan itself started venting/dripping oil. Seems like an excessive amount of mist is venting out my breathers. Bike is an '05 with 30k miles.

 

The goal is not to collect the oil and return it to the motor. The oil will never really make it back down to the motor even if the vent lines are facing up and even if it could you would not want to have that oil make it back to the motor as it is likely contaminated with moisture. The reason you want to route the lines down is so that oil doen't collect in the lines and absorb water and make the yellow milky nastiness mentioned above. Most of what comes out of a catch can should be water not oil. I drain my catch can every couple weeks and there is very little oil. Mainly water and milkshake. My vent lines are clean as a whistle.

 

Yes, that's what I'm saying, that any oil that comes back from vent hoses pointing up would just accumulate at the breather outlets, it cannot drain back into the motor. So, you'd end up with milky sludge as epswing says happened to him.

John

 

Ah. Ya. Sorry. I didn't realize there are mutliple conversations going on in this thread.

I think one of the big issues is the breathers are bigger than they likely need to be. My current setup from DK has very small outlets from the breathers which was concerning to me initially but I didn't notice any really issues from it in the end and they run that setup on much bigger engines as well.

 

Correct. In a previous life, I had the hose going upwards and when enough oil accumulates at the breather bolts, it would fume and my bike would look like a choo-choo train

 

If your catch can is filling up more often than every 2000-3000 miles, it is probably for one of the 3 reasons listed below:
1. Lots of short rides, especially in cooler weather, where the engine does not get hot enough to burn off the condensation.
2. Oil level is overfull in the oil tank
3. Engine has worn parts that are letting oil go where it shouldn't.

If you don't want to address any of the above, get a filter and replace the catch can with a filter, located down low.

That is what I run on my Sporty (photo below) and works great.



I also run that on my TG and it is super easy to clean whenever you wash the bike. No removal needed. Check out the video below.



Kevin

 

People have been pointing out the problems they perceive with my DYI - no catch can head breather system. My system has worked for years and many miles performed flawlessly. One member pointed out there is no drain hole below the umbrella valve, jokingly, I said it's gotta be FM . . . frickin magic. That was before I had my 3rd cup of coffee. The 2 BIG DRAIN holes in the head NOBODY talks about. The PUSHROD TUBES drain right back down quick. Do I need to spend money on an aftermarket part when I can accomplish the same results with ingenuity and $10. HELL NO!!!! With that, I'm done here