Since the midsixties with pcv systems vacuum is applied to crankcase. I remember the big debate over it and road draft tube!
Many were going to disconnect and no way running that commie crap!
Turned out it kept engine, oil, and environment cleaner! This is automotive engines.
Harley engine I've not had apart and not sure how engineered. Is there a filtered intake of air into the crankcase?
I'm not liking this breather system without a vacuum. My opinion goes with engine builders and wanting evacuation and roaddraft system isn't clean and providing a constant vacuum.
Yep, I'm a over thinker!

 

The V twin has some challenges a true boxer engine has where the pistons approach the crank case essentially together causing pumping losses. In my shovelhead theres a rotating (timed) shaft with a breather window in it to relieve this buildup of pressure as the pistons come down. Im not sure how effective actual manifold vacuum would be with an automotive PCV system because of the size of the manifold and no plenum. I thought of the race car evacuation setup with a one-way check valve in the exhaust but I don't think it really needs it.

 

more than two years later not a drop of oil WITHOUT hose clamps

 

this was my original post and how I did it.....still works GREAT

 

part numbers to do my mod
any other combination of barb/hose may NOT work......this combo is meant to be used WITHOUT clamps

 

Guess I'm missing something. Of course there would be no oil in the air cleaner, it's routed to the ground. Don't need clamps with barbed fittings either. This solution has been around since forever. Nothing new here

 

Obviously the whole point of this entire thread is to get the oil out of the air cleaner. And there are many solutions. Not saying mine is better than anybody else's. This is just how I DID IT. And there will be
more riders eventually doing an AC breather mod to their bikes, so they may want to know how things are working down. Lot's of posts about "how I did it". Not everybody's solution
will hold up over time. And there are barbs, and there are barbs. Not all barbs are meant to be used WITHOUT hose clamps. The ones I used ARE. And two yeas / 20k later everything is holding up PEFECTLY. I like it when I read a post and get an update from down the road about how things are working out. I think others might like to know too. BTW what kind of bike lift is that?

 

I see that you later removed the airline separator because you smelled fumes. How did the airline separator provide any breathing? Looks air tight to me,unless the rear top hole was left open,which made the separator worthless.

 

Well,I've torn down a lot of mid'60s -'70s pcv equipped engines,and the piston tops and valves were usually so covered with carbon they took a ton of work to clean them up and make them useable.Maybe the crankcase was cleaner,but not the combustion chambers. I spent a lot of hours scrubbing pistons and valves with a steel wire brush on a drill.

 

15-18 lbs vacuum on a car engine,unplug the pcv hose and they'll die,or barely run,because of the intake leak.Hell,intake vacuum was used to run wiper motors for years.Only back then,when you step on the gas vacuum dropped and your wipers quit for a few seconds.