03cranec
XS400 Member
I have what I thought was a regulator issue with my 1980 xs400G, but I just replaced the regulator and I'm getting the same behavior, so I'm wondering if it could be something else. Here's the story:
- I've got a topped off battery that reads 12.5V across the terminals
- When I put the key in, the battery drops to 12.3V - this seems normal
- Once I start the engine, the voltmeter is unable to get a reading anymore. The display just freezes on whatever the last number shown was. I tried it on the 20V and 200V ranges and got the same result, so it's not maxing out the range.
- I the resistance readings on the alternator are all good. I also checked the AC current coming over the 3 white wires from the alternator and I'm getting 40-100V+ when I rev the engine, so this seems all good.
- Resistances on the rectifier all check out so I don't that's the issue.
- By process of elimination, this left the regulator, so as I said, I just replaced it - but nothing changed. I got the regulator used off ebay, so there is a chance it is bad as well, but it supposedly came from a working bike.
So here're my questions:
- What might make the voltmeter put out non-sense readings like that only when I start the engine?
- Is there any way to confirm that this is / is not a regulator issue?
- Do I potentially have no issue at all? Or just a bad voltmeter?
A little back story for more context: I recently replaced the whole alternator/stator unit because I was having charging issues. When I got in there to replace it I found the wire frayed almost apart on the old stator, so I know this was causing the original issue. I only discovered this new odd voltmeter behavior when I went to check the installation of the new stator. Right after the installation the voltmeter (a different voltmeter than the one I'm using now) did show 15-16V across the battery terminals with the engine running, so that's when I ordered the new regulator. I'm now unable to reproduce that behavior though. I may not have any issue here, but I'm afraid to ride the bike as is without confirming that my battery is not under or over charging.
Thanks everyone! This forum has been super helpful on a couple easier issues I've had, so I'm hoping someone can help me out with this trickier one.
-Chris
- I've got a topped off battery that reads 12.5V across the terminals
- When I put the key in, the battery drops to 12.3V - this seems normal
- Once I start the engine, the voltmeter is unable to get a reading anymore. The display just freezes on whatever the last number shown was. I tried it on the 20V and 200V ranges and got the same result, so it's not maxing out the range.
- I the resistance readings on the alternator are all good. I also checked the AC current coming over the 3 white wires from the alternator and I'm getting 40-100V+ when I rev the engine, so this seems all good.
- Resistances on the rectifier all check out so I don't that's the issue.
- By process of elimination, this left the regulator, so as I said, I just replaced it - but nothing changed. I got the regulator used off ebay, so there is a chance it is bad as well, but it supposedly came from a working bike.
So here're my questions:
- What might make the voltmeter put out non-sense readings like that only when I start the engine?
- Is there any way to confirm that this is / is not a regulator issue?
- Do I potentially have no issue at all? Or just a bad voltmeter?
A little back story for more context: I recently replaced the whole alternator/stator unit because I was having charging issues. When I got in there to replace it I found the wire frayed almost apart on the old stator, so I know this was causing the original issue. I only discovered this new odd voltmeter behavior when I went to check the installation of the new stator. Right after the installation the voltmeter (a different voltmeter than the one I'm using now) did show 15-16V across the battery terminals with the engine running, so that's when I ordered the new regulator. I'm now unable to reproduce that behavior though. I may not have any issue here, but I'm afraid to ride the bike as is without confirming that my battery is not under or over charging.
Thanks everyone! This forum has been super helpful on a couple easier issues I've had, so I'm hoping someone can help me out with this trickier one.
-Chris