Hi All, My '77 R100RS stopped running: points, oem coils, single plugged, essentially a stock ignition system. I departed Priest Lake, ID in the cool of the morning. Rode about two hours to Spokane and the day started warming up. On the ride it missed a few times at about 80 mph. I stopped in Spokane to visit a friend and get lunch and then headed west on Hwy 2. Temps rose to about 95 degrees and the miss became frequent within 30 miles. I pulled over in a shady spot and proceeded to clean all the connections. The point gap looked good, the plugs looked good, there was gas in the tank. With a bit of optimism I headed back on the road and the bike stopped running w/in a mile. The battery was strong as it gladly cranked as I looked for spark (orangish), swapped plug wires, etc. The starter would spin but it wouldn't fire. I walked the bike back to town and trailered it home (after a friendly ride). When I got home I unbuttoned things, cleaned some more connections but didn't feel I made any notable changes. The primary side on both coils measured w/in spec (1.3 ohms) and the secondary measured 6.7K ohms on one side and open, .6M ohms, on the other. I shot a bit starting fluid (gasp) into the carbs and it fired. I made sure the bowls filled with gas and it ran as good as always. I've ridden it about 50 miles in 65 degree temps and it's running great. Now when I measure the coils both are in or near spec (1.3 ohms and 6.7K ohms) on both primary and secondary tests. User error on the first test is possible but I must have tried a half dozen times. Spark plug wires measure 5K ohms. Spark plugs haven't changed from run/won't-run/run. Likewise with the battery. 1) Is it possible that one coil failed in the heat and kept both cylinders from firing a spark strong enough to run it, even on one cylinder? I don't understand the symptoms of single coil failure. 2) Could a bad ground cable be the cause? I'm stumped as to what may have kept it from running. I haven't yet checked valve clearances but I'm guessing they're okay...guessing. Thanks for any ideas and suggestions as to what kept it from running or diagnostic tests I can run to keep it running.