I have seen a few threads on here regarding oil in the airbox but would like to expand the conversation a bit.
So I never had an issue with this until I switched to a DME low pro pan. I measured my oil level the same way as before and it takes about the same amount of oil as it did previously. I'm not sure if windage or something is effected or what the issue is. It would seem after launches or sustaining high rpm runs I would have an FI light come on and be burning oil as it was visible in my exhaust. When it happened I would head to the garage and open her up, every time there was oil in the airbox and it had obviously came from the crank case vent hose.
I did some checking on here and guys in the past have plugged that port on the airbox and ran a line to a catch can or a line up the tail with a breather on the end (this is how I am currently setup).
However in doing this I have learned that you take the vacuum away from the crankcase that is generated by the intake (I know right, Captain Obvious and all) and blowby and other gases remain in the crankcase that need to be sucked out. Obviously for this application from the factory it is just sucked into your motor and burned along with your nice clean air and fuel, but we don't really want that do we? Or do we, is it important to have some sort of oily misty air running into the intake for intake and cylinder lubrication or does it get enough from the oil circulation design?
I plan on splitting my cases and taking a notch out of the plate below the vent tube to allow for oil to drain back down easier as I have also seen on here. Hopefully that stops the puking. Then I would like to either return the line back to the airbox to reestablish vacuum, or purchase a pump and leave the airbox capped off.
I know people like to "keep it simple" and all but I feel that I am at a crossroads that requires something here.
How much vacuum is "needed" for proper crank case ventilation? I did some research but most of what I could find pertains to cars not bikes. They say there is even a power increase when running a level of 10-15 inches of vacuum. I am not concerned about making power nor do I wish to debate that. I am concerned with ensuring the crankcase is evacuated of blowby and etc and also with not getting oil in my airbox. My hypothesis is that somewhere around 6-8 inches of vacuum would be sufficient. If that amount is not generated by the airbox I think I will purchase a pump and regulate it to somewhere around there (unless this discussion proves that it is important to have some sort of oily air going into the intake).