1977 Restoration project

Where in Georgia are you?


Never mind. Looked at first post. WA state?

Thought maybe you were close to me. Says Georgia USA.

Moved to WA state 6 months.

Alright everyone. Good news.

I got the bike started yesterday. Had a friend filming and taking pictures so I'll post them tomorrow once I get the files from him.

Anyways, the bike is NOT CHARGING AT ALL. Battery voltage at rest is about 12.5 volts and its not just a surface charge because the battery easily drives the starter motor (I also did these tests jumped to my car battery).

When I say it doesn't charge I mean that literally there is NO voltage change when I rev the bike.


Here is what I have done to investigate:

1) Performed a slap test on the rotor. Successful.

2) Checked alternator brushes. They are each longer than 1/4 inch. They also make strong electrical contact with their respective slip ring

3) Slip ring resistance. Was a between 5 and 6 ohms.

4) Stator resistance. Resistance betweeen each combination of white wires on the stator was 0.4 or 0.5 ohms.

5) Voltage at positive alternator brush. The voltage was approximately 0.6 volts less than the battery voltage. Curly suggests this is a problem. I haven't been able to find where the voltage drop occurs but I want to skip this for now because I figure this would not explain why there is absolutely NO CHARGING going on. I figure a low voltage at an alternator brush would cause weak charging, not NO charging. Is this right?

6) Stator output. With the stator PLUGGED INTO the wiring harness I checked the AC Voltage on each combination of white wires. They were all approximately 20 volts.

I think the problem is with the last test. According to Curly's guide it should be about 11 VAC, not 20 VAC. Curly suggests this means a bad rectifier. Is this correct? Can someone explain how a bad rectifier would result in absolutely NO charging.

Also, anything else I should check.

Thanks guys,
Adam

Rectifiers from the electronics market that substitute are dirt cheap and work more efficiently because of their newer design (less current draw). You should upgrade it anyway and since there's an indication it may be bad, I'd just do it. Here's one for $8 .....

http://www.amazon.com/Aluminum-Heat...&keywords=3 phase rectifier&tag=5336653628-20

I'm going to do just that.

5twins, can you explain why I higher than normal stator output would imply the rectifier is bad?

Also, does this explain why there is NO charging?

The reason I am asking these questions is because I don't want to wait a week for the part to arrive and find out I still have the problem. I'd like to fix all potential issues in parallel.

Best.
Adam

I'm afraid electrical isn't my strong suit so no, I can't give an explanation. Maybe RG or XSLeo will see this and maybe they can explain it better.

I believe 5Twins has it, bad rectifier, or bad rectifier connections. You can do the test in the 'charging guide' to confirm.