There is a drilling in the side of the plug in which you can put a size 3 Allen key or a Torx key T10 (usually found in the your BMW toolkit) in order to fit and remove it.
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Also referred to as oil filler cap.
Cover for the foot brake fluid reservoir, CNC machined of...
These aluminium parts cover the big holes above the foot...
This cover for the axle pivot for all new BMW R1250RS bikes...