Being of the age where "real" cars and bikes have points, distributors, and carburetors, well... this was a learning experience. But thanks to the MANY helpful hints, links and advice from fellow XS'ers, I have been able to figure out how to diagnose an intermittent ignition problem. So, I hope to consolidate the various bits of information gathered, and put it all in this thread. First, some basic electrics: dc electrics can be thought of as a "loop"... electricity "flows" from one battery terminal to the other terminal (see pamcopete below). The battery is the storage unit, providing electricity when it is needed for starting, both the electric starter and the electricity for the ignition. And thank you PAMCOPETE for the following: Any testing of electrics will involve testing, in a bewildering array of options, how that electricity does its work. Basically, we are looking for (a) voltage, or (b) continuity. Using those two simple electric tests, we can do a helluvalotta troubleshooting! I find these three tools to be the trick: The red meter is a digital multimeter, sometimes called a VOM or a DVM or DM and probably a lot of other names. There are two scales that interest us: voltage, and resistance/continuity. Voltage indicates the presence of electricity, and is measured with the + and - probes. It is good practice to attach the (-) to the black (-) post of the battery: that way, your voltage reading is an accurate voltage in the "loop" back to the battery. A GOOD contact is always necessary, so don't be afraid to scritch and scratch whatever you are probing to make sure you have a good reading! That little thingy with two thin red and black wires has proven to be quite trick: it is an LED (make sure your LED is for 12Vdc (volts direct current) nominal). The trick thing about LED's versus a "standard" bulb is that it reacts instantaneously to current, so when you hook it up to the pickup unit, for instanced, it will flash very quickly and let you know that the pickup is working. The thing on the left is a spark tester. GET ONE!!! It will so-easily tell you whether you have spark, and this can eliminate a gazillion questions about whether we are trying to fix a spark problem or a carb problem. Since our TCI system uses the screw-thread type of spark plug, I had to modify this particular tester since it was designed for the fat-top spark plugs. I simply filed the blunt probe to the point where the spark plug cap would grab it. You screw the fat-top onto your bike's plug, and clip the tester on. EASY This is what it looked like "before": They cost about $6, so GET ONE!!