I've used the 'vent' system on the last three bikes--before those, my bikes were so old they did not route crankcase gases into the intake system.
My experience is nearly like CVORK's. After reading this, I went out to check for any drips below my vent-to-earth system--nothing. I did wipe the end of the vent tube and there was a trace of oil substance on the end of the tube, that's it... and I've been doing some heavy PV tuning the past week or so including some +3digit freeway runs... a small trace on the end of the vent tube, that's it. I have noticed a drop on the floor a day or so after some serious two-up touring at constant freeway speeds for extended periods of time. But not solo.
After setting up the external vent system on the first TC I had, I've never looked back.... it just makes no sense to my limited combustion engine experience to feed an oil-heavy mixture into the intake system... but that's just me.

 

That is how mine is. Simply vent to earth. No issues. No fancy filter or catch can. Other than my high flow, Street Cannon's and factory download, the bike is stock. I ride solo. Since I hold a CDL w/ tanker-hazmat endorsement I stay at or below the posted speed limit. I cannot afford the luxury of a speeding ticket.

 

Yes, I posted a pic of the hose barb packaging and told you what drill size and tap to use.....The hardest part was figuring out which drill size to us for the hose barb and thread pitch. All the work has been done.....except of course doing the tapping which I did a practice run on a piece of bilet aluminum.

 

Got by catch can installed

Hopefully it works out as planed
Tight fit but it did fit

 

The carbon build up on some of those pictured pistons is most likely from fuel. If you were getting that much oil in the combustion chamber to cause a buildup then you would be using oil at the same rate as you are using gasoline. The little bit coming in from the breather hoses does not cause a problem, unless it is flooding in. If it is flooding in then you have other problems such as a problem with the umbrella valves in the rocker boxes or excessive blow-by. On the one piston pictured there is a cleaned spot at the front edge which usually signifies oil washing off the cylinder walls onto the piston, which cleans that part of the piston down to the aluminum. In other words, using oil. Its a sure way of finding out an engine has ring or cylinder issues. Maybe there is a different reason for the pictured piston being clean on one spot.

Since the mid 90's there is less detergent in gasoline so carbon build up is more likely unless you are using Top Tier fuels. Stay with BP, Shell, Conoco, Chevron, Phillips 66 and other quality brands and that won't be as much of a problem. http://www.toptiergas.com/retailers.html

Also, not putting some sort of filter on your breather hoses invites dirt and grit being sucked back into the engine since there is some suction on those breathers. In addition, putting the by-pass breather below the air filter just gets you a fancier way of oil dripping on your engine.

Bottom line, if your bike is blowing oil then you have a problem with the engine.

 

Interesting depiction to say the least

I ONLY use top tier fuel and more specifically not a tank of fuel has ever been pumped into my tank from any source other than Shell, EVER for over 22k miles.

This blow-by has been an issue for a very long time and is certainly nothing new to the VTWIN engine family.

I don't use anymore oil in this 2012 than I ever have with any of my other 9 bikes in the previous 18+ years. Well except for my 67 XLCH, that thing used more oil than fuel .

 

I disagree with about 90% of your post...

 

You can disagree all you like but what I wrote is factual. I worked in auto and truck repair for many years and saw a lot of what I spoke. Car and truck engines have been running positive crankcase ventilation systems since the early 1970's and if oil in the intake was a real problem then car and truck engines would show it real fast. The old style breathers mounted on valve covers would usually leak oil eventually.

For what its worth, I have no oil leakage out of my SE air filter, no oil blowing on the pipes or engine and no buildup in the throttle body and have run for many miles at a time at 80-85 mph and still got no oil usage or leaks out the air filter so it is not a normal thing for a twin cam to be blowing oil out. And I run the synthetic (Syn3) oil level to the full mark. What is causing it on individual bikes may be different, but there is a problem. Most of it may be the umbrella valve and too much oil getting in that breather system. With all the cobbled messes for breathers I have seen on here, I have yet to see one person pull the rockers and change out the in head breathers to see if that is the culprit. Maybe its worth a shot.

 

and to my knowledge they've always been water cooled which injects a completely different set of factors into the equation.

so because you got a Wednesday built motor or should I say the perfect HD motor, that means it's not a problem for hundreds of thousands of others? I think not.


to my knowledge the only ones that should not be run to the full mark are the softails. Mine runs at the full level ALL THE TIME.
yep there sure is. it's called the EPA!
I have wasted time in changing breathers to no positive effect. I drilled out the rocker support plates to no effect. Don't be a hater because you don't take the time to fix what HD and the EPA has screwed up on YOUR bike. Show me a video capture of your piston tops with a borescope camera and then I'll believe you don't have the same problem everyone else has.

 

I had a 1962 ford that had a hard pipe crankcase vent routed under the car to atmosphere. No vent, no catch can, no BS. I never noticed any more dirt in the oil of that car than any of my newer cars that had oil residue in the carb.


When I got my bike, the crankcase vent was set up to atmosphere. I did some changes to the bike this last summer, including a new air cleaner assembly. I have not modified my new air cleaner on my bike to vent the crankcase vent to atmosphere, but plan on it before summer.