AIRBOX BREATHER MODIFICATION

Oil in the airbox seems to be a problem on all stock XB models leading many owners to fit external catch cans which soon fill with oil sludge made up of oil and condensation.

My analysis of why there is a problem is that intake-airflow is mainly through the left rear of the standard airbox, then through the filter wall on to the intake trumpet. On the way the airflow roars over the top of the breather tubes and sucks oil up from them through venturi-effect. The left breather is from the hotter rear cylinder which worsens the situation.

My simple 2014 modification involves fitting 3/8” PVC elbows into the stock breather tubes plus short 3/8” bore oil resistant hose extensions which run forward to just past the mid-point of the intake trumpet and end under the trumpet flaring.

This modification is almost perfectly effective. At every 8,000km service I check that all is well with the modified hoses, their elbows and cable ties and there is never any oil to wipe away other than a small dribble in the groove where the flexible intake trumpet passes through the airbox floor.

At the 96,000km service all is still perfect with this mod. A pity Buell hadn’t thought of doing it in the first place.