Dang-ddiddly dang it! The old '78 R100 had finally started to look like a trustworthy bike after much effort - and last week I had done a 60 mile loop on it. So, I figured a wash and polish and fresh tank of gas for another 60 mile loop before I retorqued the heads and rocker arms after replacing the push rod tube seals and head gaskets and de-carboned the pistons was going to be easy-peasy. I am glad that I decided to do some more local miles before venturing too far from home this weekend, as it shut down totally coming down a hill about 8 miles from home.
Fortunately a friendly guy gave me a lift back home where I got my truck and trailer and retrieved my own dead airhead, which had absolute "0" electrical activity when it conked out.
Examination in the garage seems to indicate that the main/starter relay connection 87 in the relay socket was corroded (probably from the leaking m/c when I got it from the PO), and the vibration from riding on 5 miles of gravel road was enough to cause it to stop making contact. So, I had battery power to one terminal of the relay, but no power to anything else on the bike in order to light things up to start it. Grrrr. I'e managed to clean it up pretty well and it lights and starts fine again now, though I've now managed to screw up the power connection to the horn relay in the process, and will have to go back in to fix that... May have to see about replacing the whole relay socket assembly somehow to ensure things don't go bad again further away from home.
Has