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Re: GT380 Alternator Rotor Removal

Posted: Sat Aug 12, 2017 10:45 am
by miked914
12 Volt (battery voltage) IS going IN (from the red battery wire which is in the same "clip" as the 3 yellow stator wires). So I've confirmed that 12 volt is going into the RR, but nothing on any of the output leads Orange or Green

Re: GT380 Alternator Rotor Removal

Posted: Sat Aug 12, 2017 11:21 am
by Alan H
The red wire is FROM the rectifier. You need 12 on the orange.

Re: GT380 Alternator Rotor Removal

Posted: Sat Aug 12, 2017 11:25 am
by miked914
I mis-spoke on the red wire. The red wire that is part of the clip that also has the 3 yellow stator wires has 12 volt power coming out of it and going into the RR

Re: GT380 Alternator Rotor Removal

Posted: Sat Aug 12, 2017 1:16 pm
by Alan H
No it doesn't. The red wire comes off the positive terminal FROM the rectifier and goes TO the battery. You will pick up battery voltage on this because it is connected directly to the positive terminal of the battery. This wire does not feed the RR, the RR feeds it.
You need power on the orange to make it all work as I have said several times.
I suggest you read all the comments from thread start again.

Re: GT380 Alternator Rotor Removal

Posted: Sat Aug 12, 2017 1:28 pm
by miked914
Ok, If that red wire feeds FROM the RR, then how would the Orange wire FROM/OUT OF the RR ever show voltage without the bike running? Something has to be feeding voltage into the RR with the ignition ON but the bike not running.

My RED wire is spliced with one end going into the RR and the other leg running directly to the battery. This is why I would be showing the 12 Volt.

I swear that I've wired this exact way in the past and never had an issue.

Re: GT380 Alternator Rotor Removal

Posted: Sat Aug 12, 2017 4:13 pm
by Alan H
READ MY PREVIOUS POST. THE ORANGE POWERS IT. THAT'S SO IT SWITCHES OFF WITH THE IGNITION SO THAT THEBATTERY DOESN'T DISCHARGE.

Re: GT380 Alternator Rotor Removal

Posted: Sun Aug 13, 2017 5:11 pm
by miked914
OK, I've got 12volt going INTO the RR via the Orange wire. But still nothing at the Green or at the brushes/slip rings.

Re: GT380 Alternator Rotor Removal

Posted: Sun Aug 13, 2017 6:29 pm
by jabcb
If you have 12V on the R/R orange wire & the R/R black wire is properly grounded,
then you should get a 12V reading when you have 1 meter probe on the orange wire & the other meter probe on the black wire.

If you got that reading, then check the voltage on the green wire.
You should get a 12V reading when you have 1 meter probe on the green wire & the other meter probe on the black wire.

If the R/R passed the first test (12V on orange) and failed the second test (0V on the green) then you likely have a bad R/R.


I used the same R/R on my GT380 project.
Mine worked. I got a good ~14V. Then in climbed up to ~14.8V & after a bit it climbed up to 15.3V.
I emailed Electrosport & they told me to mail them the R/R for testing & replacement.

Perhaps Electrosport has a batch of R/R with some defective units. (They are made in China.)

Re: GT380 Alternator Rotor Removal

Posted: Sun Aug 13, 2017 8:15 pm
by miked914
This could be the case then (Bad RR) as I'm getting nothing on the green wire.

I'll go triple check the grounds again but I'm fairly certain they are sound.

Re: GT380 Alternator Rotor Removal

Posted: Fri Aug 18, 2017 7:24 am
by jabcb
Wanted to get the GT380 running & on the road without waiting for a replacement from Electrosport.
So I bought a second one & I get the same 15.3V. With lights (25/35W headlight + LED taillight) I get a better 15V.

I suspect the ESR770 has some minimum current it sends to the field coil, which might be fine for a GT750 with its big battery.
But the minimum is too high for my GT380 with its tiny old battery.
(Maybe the Chinese manufacturer made an unauthorized part substitution.)

There aren’t may posts on this forum about the Electrosport R/R.
But the Electrosport R/R for the XS650 looks identical except for the use of different wire colors.
There are a lot of posts on the XS650 forum with lots of negative opinions.

Also interesting, the R/R on early XS650s powers the field coil, and the R/R on late XS650s grounds the field coil.
This could explain miked914’s issue. The guts of his R/R might actually be for a late XS650.


At this point I’ve taken the sure bet solution and ordered new modern rectifier and regulator from Oregon Motorcycle Parts.
Am undecided on what I’ll do with my two new Electrosport R/Rs.

Re: GT380 Alternator Rotor Removal

Posted: Fri Aug 18, 2017 9:34 am
by Alan H
Might even be an idea to put standard lights on to increase the current draw. That would have the effect of dropping the battery voltage a tad. Or even a pair of running lights if you don't bother about originality too much.

Re: GT380 Alternator Rotor Removal

Posted: Fri Aug 25, 2017 2:49 am
by jabcb
Installed the rectifier & regulator from Oregon Motorcycle Parts. Used the relay mod as I did with the ESR770.
Task done — got a little over 14.1V

Re: GT380 Alternator Rotor Removal

Posted: Fri Aug 25, 2017 6:49 am
by Alan H
Great news. Now what will happen next..........
Old bikes don't you just love 'em?!?!

Re: GT380 Alternator Rotor Removal

Posted: Fri Aug 25, 2017 2:24 pm
by sportston
Alan H wrote:Great news. Now what will happen next..........
Old bikes don't you just love 'em?!?!
Oh yes, but sometimes its a love/hate relationship when they don't work. :lol: