Boxerworks.com

That`s right Jean, it`s an excellent tutorial. Rob is going to get to know Boxer Electrics as good as I do ,soon.... BTW, It`s very informative to read Rob`s posts,glad you`re here Rob! You too Jean !

I've been trouble-shooting electrical systems for decades, Audi, VW, Porsche, BMW, etc. and more recently, domestic and asian cars.

When it comes time to find a fault with a airhead charging system, I've developed a fail-proof method that saves a lot of diagnostic time ($ for the customer); I can tell him very quickly exactly what it's going to cost.

My method may not be 'correct' in the eyes of many electricians, but it sure saves a lot of shop time.

Before doing anything I load test the battery and inspect the terminals;
You won't get a proper charging voltage reading if the battery has a bad cell or is deeply discharged.

If the battery is OK...

... I simply swap the regulator with a known good one.
It's the easiest component to access and swap, and a very common fault.
For this test, you don't have to install the replacement, you can just plug it in.
I check the bulb circuit by grounding the blue regulator wire (if the bulb is not working at all)

Next I go to the rotor, easy to test for open or short without removing anything, and I get to check the brush condition at the same time.

Next the stator, fast and easy to replace, but RARE failure,
I've seen a few stators 'test' good, but still cause the light to flicker or glow dimly.
Takes less than 5 minutes. NOTE: Not all stators are interchangeable.

Then, without removing or disconnecting anything, I check for power (on the bottom half) and ground (on the top half) of the diode board, and do a visual inspection of all it's wires.

If none of the above fixed it, I can confidently inform the customer that he NEEDS a diode board, and mounts, etc. and give him an exact estimate.
Total shop time for diagnosis; 20 to 30 minutes

The reason I leave the diode board for last ( IT IS A VERY COMMON failure), is that it's sometimes timely to remove and test.
Often, the rubber mounts break, then the starter cover, air filter, etc. needs to be removed to replace them.

The only thing that should preclude readers here from adopting this method may be restricted access to spare parts.

GSPD Your`e great also!

For a shop, the primary concern is labor cost. For most home mechanics, the primary concern is parts costs. So, it's not surprising at all when the favored approach for a shop may be different than the favored approach for an individual. But, that doesn't mean that gspd's technique wouldn't be a great one for someone who happened to have the necessary good parts laying around. It's especially handy for someone who does not feel confident in electrical diagnosis. The "replace and see if it gets better" technique is one that many people can be comfortable with even if they are very apprehensive about getting into the electrical side of the bike.