Greetings. I've been riding motorcycles on-and-off for 40 years (!) and am only now finally getting around to finding an airhead boxer. Not too interested in the monoshock R80 derived later bikes--although in many ways they may be "improved"--but rather am looking for a nice /6 or /7. I've found a nice clean one not too far away from where I live. I've done a bit of reserch on common issues with these bikes but one thing I am finding is that few BMWs of this vintage seem to have had the valves re-done to handle unleaded fuel. Several of the bikes I have inquried after have 50-60 thousand miles with no problems running on unleaded. It this typical? Also, other than checking the usual things--mantainence history, obvious oil leaks, smoking, knocking/noises, ride quality, cosmetics--are there specific problem areas I should look for in a boxer of this vintage? I really want one of these and am in no rush--I want to find the right bike for me. Thanks for your input!