Grand Prix 125
Main Motorcycle: 2013 Triumph Thunderbird
Join Date: Feb 2019
Location: Doha, Qatar
Other Motorcycle: previously had HD Deluxe
I think I am doing the right thing spraying the inside, because the oil should go on the air intake and not the air outlet (from the filter perspective). Please see how the filter configuration is in the T-Bird.
From manifold perspective, if you spray the oil on the outside of the filter, with the strong suction from the engine, particles from the oil will probably go into the intake manifold (which is what I think may have happened to my bike).
How is it possible that for both Harley and T-bird K&N filters, you spray the outside part when one sucks air from the internal side and the other does it from the external part of the filter? Not at all logical. I even believe K&N should clarify this on their filters.
The same applies for cleaning. If you are forcing water from the inside to outside in case of the T-Bird, you are actually helping dirt particles to get stuck (because dirt particles are trapped on the internal side). Whereas in Harleys, you force water from inside to outside because dirt particles accumulate on the external part.
But if it works for you guys, then good for you.