My 94 K75 has a clanky rattle between 1200 and 2000rpm. Noise is not there when the engine is run without the alternator. New alternator, monkey knutz, and drive dog(the splines on the old one stripped out for some reason) and the damn noise is still there. Been there for the 14,000 miles I've put on the bike.
I am beginning to think is may be the bearing in the intermediate section or possible the anti-backlash spring in the starter drive. In any event, it doesn't appear to be hurting anything, so I am going to wait until this winter to get into the engine to check out these parts.