Getting around to the throttle body my upgraded filter backplate does have a hole, closed with a brass plug, for the oil breather tube to connect to the filter backplate via a 90 degree elbow.
I searched but didn't find any explanation why the oil breather line is not connected to the intake filter. I have seen many tales of the breather tube 'puking'. Is this to prevent fouling? If the breather just dumps a little oil in the air intake what does it harm? Is this issue associated with overfilling the oil? (my 90 Sportster will breath so much oil into the filter after steady high rpm travel that the carb will foul and engine quit).
On the one hand, the higher elevation of the intake mounting might keep less oil from rising far enough to enter the filter assembly. On the other hand, the suction of the air intake might draw more oil up the breather hose.
I also note that some people route the breather hose all the way over the rear tire and out the back which certainly raises the breather hose fairly high. Are people sure any oil escapes the hose that way? Any idea whether more or less than when the hose is mounted low, to a filter, like the bottom bolt of the front engine frame mount?
