M6 - 0.85 pitch x 25mm Hex Bolts
10mm Across Flats
4mm Hexagon Head Depth
Threaded 20mm
Special therad for use on Gearbox assemblies and Engines peculiar to BMW. Possibly only ever used by BMW, this thread pitch was long forgotten and tooling was only made recently available to ourselves.

Applicable models inc: R2;3;4;;5;6;7;11;12;16;17;20;23;32;35;37;39;42;47;51;52;57;61;62;63;66;71;75.

May be on other models not listed and may not be applicable to all the models listed.
Chances are this will be the thread you can not identify.

16 per assembly