Barn finds are common, so I think this question may be of interest to a few of you. I have two 550's with good titles, one of which will be Cafe-itized this winter. One is a '77 bike with low milage but heavy rust on one side, as can be seen in the photograph above. The heavy rust is confined to the area you see. Apparently the bike, which has a 6" extended front end with stock side stand, was laying against some old hay bales for about 8 years. Needless to say where the hay touched it and the metal got to rot away in blissful communion with oneanother. I can remove the rust with either a grinder, wire wheel, phosphoric acid, or just plain vinegar, that's not a concern. What I am concerned with is the strength of the steel and how sound the frame will be after cleaning.
My thinking is that the frame is probably sound, just remove the rust by the least aggressive method available (don't use the grinder) and get on with the build. However at the same time a little voice in my head keeps saying, "hey buddy, this is your butt on the line here and you know you drive like an idiot, are you going to trust a frame that obviously has been weakened to some extent?" What do you think?
