freddy3
XS650 Addict
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- 479
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The charging system in my '72 XS2 is once again not working (i.e., the battery drains (especially when I switch the headlight on!) and the bike dies by the side of the road with no lights, horn, etc.). Once the battery dies, if I let the bike sit for a few minutes, it'll start up again and get me home without any problem as long as I don't use the headlight.
This time, however, the problem wasn't preceded by the rectifier burning up, so it's probably something different (and not the rectifier).
Unfortunately, the 9V battery in my Fluke digital multi-meter just died as I was trying to test the resistance between the rotor rings, so I can't (yet - I'll get another battery tomorrow) report much in the way of results from the Troubleshooting section of the factory service manual.
However, yesterday, I installed a new, fully charged Shorai battery (out of the bike, it measured 14.2V at the terminals). After the battery was installed and with the engine running at 2,500rpm, I measured 13.2V at the battery terminals. When I switched the headlight on, the voltage dropped to ~12.9. Switching the headlight off, it went back to ~13.2.
As I kept testing the voltage over a five-minute period, the voltage slowly dropped so that I was getting ~12.8 and ~12.6 when I switched the headlight on (it went back, briefly, to 12.8 when I switched the headlight off).
Then, I removed the cover on the regulator and tried adjusting the screw, but it had absolutely no affect on the voltage at the battery terminals:
Revving the engine from idle with the headlight on produced no change in brightness.
So, clearly, the charging system's not doing its thing.
As you can see, the left-side alternator brush is near its minimum length limit, so that may be related:
Also, the bike DID pass the "SLAP" test, so I'm kinda wanting to point the finger at that worn alternator brush and/or the regulator (since the adjustment screw doesn't affect the voltage readings at the battery)??
Does that make sense, or should I run through the rest of the factory manual's troubleshooting steps first?
In case it's useful, here're photos of the alternator...
...and rectifier
This time, however, the problem wasn't preceded by the rectifier burning up, so it's probably something different (and not the rectifier).
Unfortunately, the 9V battery in my Fluke digital multi-meter just died as I was trying to test the resistance between the rotor rings, so I can't (yet - I'll get another battery tomorrow) report much in the way of results from the Troubleshooting section of the factory service manual.
However, yesterday, I installed a new, fully charged Shorai battery (out of the bike, it measured 14.2V at the terminals). After the battery was installed and with the engine running at 2,500rpm, I measured 13.2V at the battery terminals. When I switched the headlight on, the voltage dropped to ~12.9. Switching the headlight off, it went back to ~13.2.
As I kept testing the voltage over a five-minute period, the voltage slowly dropped so that I was getting ~12.8 and ~12.6 when I switched the headlight on (it went back, briefly, to 12.8 when I switched the headlight off).
Then, I removed the cover on the regulator and tried adjusting the screw, but it had absolutely no affect on the voltage at the battery terminals:
Revving the engine from idle with the headlight on produced no change in brightness.
So, clearly, the charging system's not doing its thing.
As you can see, the left-side alternator brush is near its minimum length limit, so that may be related:
Also, the bike DID pass the "SLAP" test, so I'm kinda wanting to point the finger at that worn alternator brush and/or the regulator (since the adjustment screw doesn't affect the voltage readings at the battery)??
Does that make sense, or should I run through the rest of the factory manual's troubleshooting steps first?
In case it's useful, here're photos of the alternator...
...and rectifier
Last edited: