the baily breather tank has a pipe from the breather hole on the inlet side to one of the top inlets of the tank the other top inlet can have a filter on it like mine or if you drill out the hole at the back of the rocker cover you have to remove it to find the place to drill as its has a cast mark on the under side

then you have a large pipe on the bottom witch drops down to atmosphere then theres an angled out let witch drains oil that it catches back to the sump via the removeable bung on the exhast side its the lower one as the one above has coolant behind it

i do not use the air box to breather its blanked off if your getting lots of oil in your air box its due to high crankcase pressure due to worn bores/ring some is expected and a drop of oil does make a lot of mess