How do I test my stock alternator

I’m just happy you guys were able to point me in the right direction to find out what was causing me to get no charge. Now I just need to know what the best route to fix it is.
 
Go back and read this comment I left you about Bob's reg/rec. He used the same rectifier and even has pics. ;)
 
Not sure where I ran the ground wire to now. There is a groove on the back of it, I slid two bolt heads into that groove and mounted it with spacers over those bolts so that it had standoffs from where I mounted it with those two bolts. Some people shave those tabs so they can use female spade connectors, I used soldered ring connectors and small stainless screws with washers, lock washers and nuts. I mounted one to the side of my plastic air box/tool box on a Honda. Maybe mount it to a thin plate, then mount the plate to the bike. It never gets hot, only warm, but that could vary depending on what regulator is used.

Scott
 
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Yeah and thanks a lot everyone. I honestly would have never figured this stuff out this quick (or at all) if I wouldn’t have gotten all the great replies.

And I’m kind of glad I took the rectifier off the wrong way because I never would have found that it was shorting itself out without removing that center bolt that goes through the rectifier. That’s where it was shorting. So basically I put it back on the bike (temporarily until the new rectifier comes) but then I took some leather off of an old welding apron I had and used it as insulation between the rectifier and the bolt on top so it won’t short out. The ground is back where is should be too.

And best of all....it’s charging. *high five*
 
Page 2, Post #33 ...........Pics and all the information relating to the 3 Phase Bridge rectifier and the wiring......... + ............all the information regarding the B type Automotive regulator for your model.

Even if your charging ok the B type Automotive Regulator swap makes the Voltage regulating more reliable with less fluctuations. Better for your battery.
 
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So to restart this thread...I bought two of the rectifiers to replace my stock one and wired it up like so. I plugged it in, started the bike, and again it wouldn’t charge the battery. I unhooked the ground from the above rectifier and ran a test lead from the ground wire to a chassis ground up by the the battery like I did with the old rectifier to make it work. And guess what, the new rectifier started charging.

Does anyone know why I’m having to do this? I’m kind of irritated because the whole reason I got the new rectifier was to update the old one and make it so I could just put the ground where it’s supposed to be on the rectifier.
 
i would think it has to be in the black wire from the brush to the Rectifier............can't test volts on an earth wire..........have to continuity test.......Continuity test the black wire from the brush to the connecton........If that checks then plug the rectifier in and test from the brush to the rectifier.........This will show if the Earth wire has a break in it...........is the brush grounding properly

Has the connector, on the stator side, been thoroughly examined for corrosion or a damaged connection? May need to remove the pins.

5twins posted the manual description, (with pics), testing resistance to the brush in post no #59........It talks about resistance.........Testing resistance is continuity testing.. Resistance is when there is a problem in the circuit and it shows up on the meter as a number. The higher the number, the more resistance...............No resistance = full voltage getting through......some resistance = some volts getting through, could be corrosion or a loose/intermittent connection........Full resistance = no voltage getting through, broken wire or connection
 
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The black ground wire from the rectifier runs to a main black ground wire in the harness. That main ground wire exits up near the coils and grounds to one of their mounts. This main ground wire grounds numerous items that tie into it inside the harness. Take a look at a '79 wiring diagram and you'll see all the stuff that ties into it. My first test would be for continuity between that ground connection on the coil mount and the black wire in the rectifier plug. If the ground at the coil was bad, it would affect lots of other components along with the rectifier. I'm thinking just the rectifier's black wire connection to the main black wire in the harness is bad.
 
Thanks guys I’ll check that out when I get home. Even when it’s charging, I still feel like I can’t get enough volts to the battery at 3000 rpm. I think the highest I can get is like just under 13v. If I rev up 4000-4500 rpm though I can get up to 14.4v before the the regulator kicks in. My battery is good and brand new.
 
Next thing as suggested by many in many threads about charging is cleaning wiring connections. Your bike looks to have some patina and would benefit from a good going over to ensure the flow of current will stayin its required path.
 
Well I found why the bike wasn’t charging up to the right voltage at 3000 rpm’s....the screws holding the stator weren’t seated tight so the stator was loose. So now it’s charging right. Still haven’t figured out the ground wire rectifier issue yet though.
 

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