Not sure why but this is normal.

 

I think you feel the pulse of air at low rpm because the air moves fast enough that the rising and falling pistons create alternating positive and negative air pressure at the tube, but at higher rpm the air is compressed and decompressed so fast inside the case that the pulsing is not noticable at the breather tube since the air doesn't have enough time to move between each cycle (at the breather tube).

 

I was just trippin because i was being blown in the face and I was standing over my bike, not kneeling next to it. I guess if it's normal, then I won't worry about it. I was just trying to figure out why I'm going through so much oil. I thought maybe if the pipes were plugged that would explain why so much oil is going out my tailpipe and why I get some dribble marks out of my filler cap. I guess I'll have to do a compression test and see what I see. Thanks for the input!

 

The breather lets air in and out of the crank case. It has to go somewhere.

The L twin configuration means that both pistons at some point are going to be near the top and bottom of their stroke at the same time. That's a lot of displacement down inside the cases.

I4s will usually have some pistons going in opposite directions, so the displacement isn't as drastic and/or noticeable.