TE 310R metal flakes on drain plug

I bought a month ago another TE 310R 2013, a really special one this time. I have it started only for 5 minutes on day one and since It ran a little poor (like an air leak, lean) and that I saw very little oil from the sight glass I decided to stop and take care of her. Started from deep wash, cleaning and greasing with dielectrical grease all the connectors, cleaning and greasing every bearing and seal (still have to do the front end ) and shimmed the valves to spec. Yesterday with the bike back on wheels I've drained the oil for the first time and the magnetic drain plug didn't even come down from the amount of metal flakes that were attached. These metal flakes are strange, however, because they don't look like bearing parts or gearbox parts: they are magnetic but if I hold them in my fingers they break so they are not pieces of steel nor aluminum because they would not have been captured. the same flakes were found on the stator pick up. The oil filter and the oil pump prefilter were free of these. They are black and, even if I cleaned them with gasoline, when I smash them between my fingers they dirty them with black. According to you where they can come from?

Pics of the stator