I don't have experience with the Krauser racks, but the BMW racks for the R65/R45s I think differs
from the rack for the big bikes (as far as the pre-85, dual shock frames go) in the area of the "arm" that
extends down toward the rear footpegs and bolts on down there. The length of the arm and orientation
of that end are different for the smaller frames, I believe. Don't have a set of each handy to compare, though....