I'm servicing the rear brake on my early '85 K100RT and the rear rotor is ready for the bin.  I have another rotor than I can pull from an ABS '92 K75RT.  The part numbers are different 206 versus 305 (last three digits for both rotors) and the MaxBMW fiche states that the 206 rotor for the K100 is "not for vehicles with Anti Block System".  What is the difference between them and does this prevent me from using the K75 rotor on the K100 final drive?

Thanks!  Woodie

The difference is the toothed ABS sensor wheel. As the MaxBMW fiche infers, you can't put a non-ABS disc on an ABS bike, but you can do it the other way round. If you don't like the look of the ABS sensor wheel, take it off

Thanks Dai!  Heading back out to the shop now to do some mechanical surgery.