I only figured it out through context and by seeing it for myself. The knobs that develop the "angled" wear actually have a somewhat concave shape - I can only assume that the concave shape inspired the name "cup/cupping".

I could be totally wrong. smile


'06 XT225, 2" hole in airbox, Z1 mod, 127.5 main jet, UNI air filter, Corbin seat, PIAA 500Hz, custom aluminum rear rack.