Owners of early BMW twins are divided into two sorts; those whose centre stand bolts have failed and those whose bolts are going to fail soon. The root of the problem is that on the pre-square air filter models the stand pivots on bushes retained by a pair of bolts which screw directly into the frame. The continued heaving on and off the stand eventually loosens the bolts and the threads in the frame will start to fret. Retapping the frame to the standard thread (M10x1.25) and replacing the bolts delays the evil day, but when I found a bolt lying under the bike only days after doing this, I knew it was time to look for a better solution.
My method goes as follows: Remove the exhaust. Clean the frame threads with a suitable tap. Obtain two longer m10 bolts with an unthreaded section slightly longer than the width of the pivot bush and spring washer. Assemble the stand, screwing in the bolts until they touch the sump. Measure the excess length of the bolts, remove and hacksaw off enough of the thread so that when assembled the bolts have a tiny clearance between their ends and the sump. Depending on how stripped the frame threads are it may be necessary to enlarge the entry slightly so that the plain section of bolt is a snug fit and can be screwed fully home. Find the fattest nuts which can be fitted into the gap between sump and frame. I managed to get a nyloc nut on one side. It's worth trying a few suppliers, some stainless nuts are available in slightly different widths to make best use of the limited length of thread. Nuts and bolts can be torqued