Someone said before that the best way to know if its working is to run premix and take the tubes from the oil pump into a catch box or bag (one for each tube). Ride it as you usualy do and see if you end up with oil in the box or bags after a ride. remember to block the openings to the carburator!! or it will rev like a nut!
They are hell to bleed as well so better run a tank of premix once you re-fit the tube to the carburator.
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feel the wind