What do I do with the black wire?

[Newbie]

I'm performing the Chrysler regulator mod on a 1978 XS650. The stock regulator has 3 wires (Brown, Green, and Black). The brown wire connects to the lower pin on the new regulator, and the green wire connects to the upper pin. What do I do with the black wire? Is it used to ground the regulator?

 

[retiredgentleman]

Black goes to ground................either the common black that runs in the harness or to bare metal of the engine or frame (not to the battery box that is rubber mounted)

 

[Newbie]

Thanks for the help.

 

[pamcopete]

newbie,

Yes, you can use the black wire in the original wiring to ground the regulator case.

 

[Newbie]

Thanks Pete

It will be a couple of days, maybe even weeks, before I'm done, but I'll let you'll know how the mod goes.

 

[Newbie]

I'm also doing the Radio Shack rectifier mod. Where do I connect the black wire and red wire that I have soldered to the new rectifiers?

 

[retiredgentleman]

Newbie;

Are you familiar with reading wiring diagrams....................they show you where to connect?

The black from the rectifiers is the same as the regulator...................it goes to the common black in the harness or to bare metal.

The red has to connect to the junction of the ignition switch and the main 20 amp fuse.

I hope you are using a connector (6 pin, with only 5 used)

 

[Newbie]

I connected the black to the black in the harness, and the red to the red in the harness on my '78 XS650. I failed to use a connector, but I was planning to solder the wires.

 

[Newbie]

The wiring diagram is very helpful.

 

[Newbie]

Still working the charging issue on my '78 XS650.....

I think I've found the problem, but I need a little guidance on what to do next.

Curly's Charging Guide Results

1. No magnetism
2. No change in voltage with the jumper wire from the positive brush to the battery
3. Voltage at the brown wire at the positive brush is 0.06V, basically nothing; I think this is my problem

I checked the voltage at the key switch connector. The results are below...
1. Red Wire 12.3V which is the same as the battery's voltage
2. Brown Wire 11.6V
3. Blue Wire 11.6V

The brown wire from the connector to the positive brush measure 0.00 ohms. I took that to mean that the circuit is good. Is my key switch bad, or could it be something else?

 

[retiredgentleman]

If you are using a chysler regulator in a 78, then you must be using nylon screws.

The 11.6 volts is acceptable. The brown wire at the right + brush should be close to the 11.6 volts. If you measure 0.06 volts then you have a broken wire or connector.

 

[Newbie]

Thank you

I am using nylon screws.

 

[Newbie]

Partial success at last,

I replaced my rotor with a new one from Custom Rewind (made the trip and picked the new rotor up in person). The old rotor was shot with resistance readings of 0.6 ohms.

I installed the RadioShack rectifiers and the VR-115 regulator. I found the regulator on eBay.

The new system works well, but I'm only reading 12.5 volts at idle. I'm reading 14.5 volts at 2000 rpms. I'm also reading 15.1 volts at 2500 to 3000 rpms. 15.1 volts is as high is it goes. Is my voltage regulator still not functioning properly?

 

[retiredgentleman]

With the switch to the VR-115, you needed to remove the nylon screws, so that the right (inner) brush is grounded again. I assume you have done that.

Its more typical to have 13.1 to 13.5 volts at idle and only 14.5 volts at 3000 rpm.
15.1 volts is high. Was the regulator NOS or used?

Are the connections to the regulator correct i.e, black is connected to common black in the harness or to bare metal...............brown is connected to the brown in the harness (load side of the ignition key.)

 

[Newbie]

Yes, I went back to the metal screws. I bought the regulator new (at least that's what the eBay ad claimed it to be) It looked new. The VR-115 had 4 wires (black, green, reddish-orange,and yellow) I connected it.....

VR-115 black to black in the harness
VR-115 green to green in the harness
VR-115 reddish-orange and yellow to brown in the harness

 

[retiredgentleman]

The voltage at idle is a variable number. The alternator is barely spining fast enough at idle to generate any current to go into the battery. If the idle was at 1100 rpm, then 12.5 volts is OK. As the idle goes above 1200 to say 1300, then you should see 13.1 to 13.5 volts.

15.1 volts at 3000 rpm is high, and may cause water loss from the battery. The high voltage could be hard on the ignition system and hard on incadescent bulbs (might burn out sooner). Was the headlight off when you measured 15.1?

 

[Newbie]

The head light was on.

It idles around 1000 rpm, so maybe I'm good at idle.

 

[Newbie]

I'm using a gel battery.

The lights shine brighter as I rev the engine.

 

[retiredgentleman]

I don't know anything about gel batteries.................never owned one.

You certainly have good voltage, so maybe just monitor how the bikes runs with the extra high voltage.

 

[XSLeo]

The only things I might add is to be sure you have a good ground on the black wire. Be sure the voltage at the brown wire at the reg is within .2 volts of battery voltage. Any less and the reg thinks the battery is low and needs charging.
1000 rpm is a bit low 1200-1500 is better.
Leo