How do I know the difference between speedbearing and a YYF bearing? I don’t know which one is the one.
I know that the yoyofactory SPEC bearings have “YYF” etched on the outside of the bearing.
Speed bearings have yyj or yyj speed or something like that etched on the shield.
I also think the YYF bearings have hard outer angles and the YYJ ones are a bit rounded.
Just my observation, bu the YYJ ones seem to spin longer stock. One properly cleaned and treated, the differences are smaller but the YYJ ones still seem to spin longer, just not by as much. I do have exceptions.
Speed bearings have 10 balls in them so they will spin longer than yyf ones.
10 ball bearings will not necessarily spin longer, faster OR smoother just because they have 10 balls in them. That has to do with tolerances in design as well as condition of the bearing.