Folks, this seems to be a serious and reoccurring problem I have frequently seen and replaced on noted (subject heading) model years... Pic below is of the black plastic (why?! - don't ask) “oil supply tubes” (2B000579 - ex GU19027500) that feed oil to the valve rocker assys. You can see the visible crack. This dumps the oil into the head, and not to the rocker spindle, arms/valves. The bike shown was taken from is a 2016. The older motors have a problematic (superseded) part #, however the newer part # does not fit/work on them - don't ask as to a solution; Not sure what to suggest.