'77 Z1000, have removed carbies and air box, K&N pods on new Keihin carbs.
What to do about crancase breather tube? Internal of air box very clean so no issues with oil/sludge, I think breather filter is unnecessary. Thought I might run stiff tube 2 or 3 inches straight up (to let any oil mist condense and drop back into crankcase) and then right angle to vent to back of bike.
Does any air come back into engine? The original vent coms into airbox before air filter so that air getting into crankcase is not filtered.