Oil pumping out the catch can

[PoorUB]

PW, what do the check valves on the breather hoses accomplish? Isn't the umbrella stopping any reverse airflow?

Probably referring to any additional venting, like a vent hose out of the oil tank. Any extra venting should have a one way check to let air out, but not in.

[pwmorris]

PW, what do the check valves on the breather hoses accomplish? Isn't the umbrella stopping any reverse airflow?

Probably referring to any additional venting, like a vent hose out of the oil tank. Any extra venting should have a one way check to let air out, but not in.

Yes.
A 120" at 12:5 is huffing it pretty good.
Not ever run the Thayer pump-no opinion there (is there anything about this pump and set up that you missed? O rings, gaskets, pump set up, etc?).
3.08 total gearing....that's nothing. Even it freeway speed, that's not much rpm at all-I run 3.48-so I am looking at additional air speed hi mph volume and pressure in, not rpm in and of itself (I'm guessing only 2,800 at 70 mph?).
If leakdown numbers are good, make sure Total oil in system is 1/2 to 1 qt low.
That means in case, in filter, lines, etc. then get the lower number.
May have to drain everything and start from scratch. I have seen guys think they are running low, but the oil is all over in the system, and they really aren't. Stock HD umbrella system is fine for a 70 hp stocker......
I "T" my head breathers, then to a one way check valve-then to catch can with vented hose to atmosphere (you have this area nailed except for the check valve). I run additional venting but for you, start with this set up perfectly set up for now.
A reverse test might be worth it. Since external head breathers are your only additional venting- block them off, make sure catch can is fully dumped, and hit the freeway and hammer it a bit getting on the slab. Ride a bit, then back to the garage, and check can.
More? Less dumping.?
You need to keep testing but have seen this on several set ups before, and it's a lack of the combo of oil, air, and pressure not returning fast enough from top end. It doesn't catch up fast enough from what is being forced up there at load, and then that additional pooled oil pressure is releasing/dumped into the head breather hoses, and dumping into the can.
I had a scary situation happen at Phoenix at a drag race. My 3 stage pump wasn't set up correctly and no where near pumped the oil fast enough. By the time I did a burnout, launched and went down the track (8,000 rpms), oil filled the top end, dumped-poured into the catch can, and sprayed up to the vent by my tank, and sprayed me with hot oil at a buck forty. Barely could see, and luckily got to the return lane-in one piece.

[rageglide]

Everything pwmorris stated   

Speaking of oil in the top end.   How much is too much?  Drag bikes run zero oil other than a few squirts of lube to the rockers, but they only run the engine for a 1/8 or 1/4 mile.

I run an SE cam plate/oil pump plus S&S travel limited lifters and my top end runs relatively 'dry'.  It's not flooded.  I always open up the vents on my builds, it just seems natural.  I would guess folks that have a lot of carry over are overwhelming the rocker box drains.  The cam plate and lifters play a role in limiting the oil to the top end.  Worn out bushings and shafts for the rockers would also allow more oil into the rocker box.  This isn't meant to be critical to N-gin.   But if to much oil is pooling in the rocker boxes it will exit the breather.  IMO

[dynabagger]

In my case I have drilled the rocker support drains 0.125", I also use a DT pump. I keep my oil to maybe 0.250" below the full mark on my dyna dipstick. No oil carry over in my catch can. I did a recent trip from Phoenix to Vancouver BC. Only water and some yellow puke to empty every two days worth of riding.
I have about 25000km on this build. Lucky I guess but I've been through the catch can over flow previously and it's not pretty. My wife's left shoe can attest to that.

[N-gin]

Thank you for the info guys.
I'll locate a gauge and do some more testing. Slow motion for now, got a lot on my plate and unfortunately bike is a back burner.
I'll get back to you guys
Thanks