My latest electrical kerfluffel

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MikeC23

XS650 Addict
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Johnstown Pa
Last week I went for a short ride, about twenty minutes, when the bike started running like ass and died. There was gas in the tank so I figured it was probably something electrical. I got it home, charged the battery, and started it back up. now the headlights wouldn't come on nor would the gauge lights. I has a spare lighting/ safety relay so I swapped that first thinking it might have been toast. No dice, but when I jumped the two wires on the relay, lights! Another ride, and it stands me again. I pushed that stupid thing home in 96 degree 89% humidity weather and dropped my pride on the road somewhere to. once I got it back in the garage I started going through Curlys charging system guide. The battery is perfect. The brushes on the alternator were in horrible shape. Replaced those. The rotor tested at 4 ohms. Replaced that with one that tested at 5.6 ohms. The bike starts now, runs great but still no headlights or gauge lights with out jumping the relay. Any thoughts or next direction of things to check?
 
Have you put a volt meter on the battery to see that your charging system is actually working? The safety relay gets activated by the yellow wire coming from the stator.
 
It seems to be holding steady at 12.5 volts. I also have a spare sator I can try but I'm not sure if it is good. Is there a way to test it before putting it on
 
It should be 14-14.5 volts at 3K rpm. You can check the stator with an ohm meter and the specs are in the charging system guide.
 
12.5 is basically battery voltage...not charging. Time to dig into Curly's guide and figure out the problem.
 
You haven't told us the year of your bike or the charging system installed. Two different stock systems were used, one up to '79 and another from '80 on. The components associated with the two differ (brushes, stator, voltage regulator).
 
OK, you should have the early charging system. That spare stator you have must be an early type as well to work.
 
If you track the problem down to the reg or rec, don't fall prey to those places selling fancy combined reg/rec units for $100 to $150. You can replace those components with a common automotive regulator and a rectifier from the electronics industry for $20 to $30. Those fancy motorcycle specific ones are a blatant rip-off in my mind. Although I'll admit, I wouldn't mind being able to sell something for $150 that only cost me about $20 to make, lol.
 
Well... It looks like it's the rectifier. With the engine running, between the white wires in the harness, I'm getting 18 volts on each set if whites. Would everyone be in agreement? 5twins, do you have a recommended part for the replacement?
 
Last edited:
So, yeah it was the rectifier. However, I became increasingly irritated with how bad the Po butchered the wiring harness so I replaced it. And the sator. And the brushes. And the relays. About the only electrical thing I didn't replace is the reserve lighting unit. I feel really good about the electrical system now and i seriously learned a ton about it!
 

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