Wiring repair

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rezachi

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Hey everyone,

I am working on my brother's XS650 (I think it is 1981, it is for sure a single reg/rectifier and electronic ignition unit) that is not charging. I'm going through Curly's list and things are getting better. I have a few random questions, though, related to repairing wiring.

First, I am finding holes in the shrink wrap that covers the wire for the positive brush. They are small, but enough that I can find them with the multitester. They are right at the point where the wire crosses the screw that secures the brush holder to the stator. This screw goes to the stator, and is therefore grounded, so I believe that they are causing random main fuse pops. I have a few layers of electrical tape wrapped around it, but is there a better way to fix the heat shrink?

My 2nd question is also stator related. Following the wire where the stator connects to the main wiring harness, the spade connectors on the white (well, black on my stator because it appears to be an aftermarket replacement, but white on the bike's plug) wires are pretty bad. Does anyone know the correct size so I can hit up a nearby auto parts store replace the connectors? I have them out of the plug, so I think I can crimp new connectors on, shrink wrap them a little bit, and stick them back in the plug.

If I get a chance, I'll post some pics of the carnage. One wire was completely broken off and the plug was melted a little bit from the other wires trying to carry the current. It looks like my brother was close to a fire before I started checking things out. Stator seems to test good with the meter though, so I'll try connectors first if anyone knows the size.
 
First question, not sure I can picture what you are saying, but how about using new heat shrink to fix the old heat shrink, or just do whatever is necessarily to insulate the wires, there are no rules.

Second question, again there are no rules. You don't need the white plastic or black or whatever color connector blocks at all. They just make it easy to test and replace a bad stator if need be. There is no reason you can't just hard-solder all the wires together, or use bullet connectors, or do whatever you want. Just remember to solder everything, merely crimping terminals is unacceptable. If you do use terminals or some type of individual connectors, get rid of the little colored plastic sleeves and use heat shrink.
 
Thanks. I was thinking of getting some shrink wrap and just doing another layer, but didn't know if there was some reason I shouldn't do that.

Here is a pic of the carnage on the stator plug.

eNBwfzU.jpg


I'm hoping someone here knows the right size of those spade connectors, I'm just awful at eyeballing those type of things. The goal is to just replace the ends on the two crappy wires and put them back into the plug. I want to keep the bike wiring harness stock so replacing parts is easy if it's needed.
 
Ok, I was able to procure the connectors from the local Carquest (part SST98, cost ~$0.50 each). They are very close to the OEM connector, but might be a smidge longer. They fit in the connector pretty nicely though. A little shrink wrap and it's almost looking like a professional worked on this.

3ixPDY7.jpg


Now, I'm still only at ~13.6 volts at 3500 RPM. Brushes are less than 1/2 season old and plenty long, rotor tests at ~5.5 ohms, and each combination of white wires gives almost right at 10.9 volts.

Running through Curly's charging system test, the voltage jumps up if I ground the negative brush to the negative battery terminal. As soon as I saw it hit 14.5 I pulled my jumper off, so I don't know how high it will actually go. Per the guide, this test implies that this issue is either the regulator or the regulator's ground connection. How would I go about verifying which one it is before buying the part? I touched a lead from my multitester to the black wire from the regulator and the other to battery negative and got .4 volts. The same .4 volts shows up if I touch from the case of the regulator to the battery negative terminal, or from the negative terminal to any ground wire on the harness. It appears that I have a bad ground somewhere. Am I incorrect with this test? There is no voltage from the frame to the negative terminal, so I'm inclined to believe the issue is with where the harness grounds to the frame.

I guess the next question here is, where does the main wiring harness ground to the frame?
 
Last edited:
You keep saying .4 volts when I think you mean .4 ohms.
What do you get when you touch the two multitester leads together?
 
DogBunny said:
You keep saying .4 volts when I think you mean .4 ohms.
What do you get when you touch the two multitester leads together?
Click to expand...
he has a good point. I recently went thru the charging guide myself, and when I touch my leads together, I also get .4 ohms. You need to subtract that number from your findings. All meters do this.
Good find on the spades. Looks like stock. A little long?
 
Negative, I do mean .4 volts. I am measuring voltage with one end at the black wire on the regulator and the other end at the negative terminal. The difference in voltage between a ground wire and the negative battery terminal is theoretically the amount of voltage that can't get grounded due to insufficient connection/other issues.

To show this another way, I did another test. With the regulator unplugged, one lead on positive battery terminal and one lead at black wire at regulator connector, I get 12.6 volts. Plug the regulator in, and check the voltage at the same spot, and I get 12.2 volts. A .4 volt difference.

I am inclined to believe now that the wiring is fine, but why would I get a different reading at the same wire with the regulator unplugged.
 
rezachi said:
To show this another way, I did another test. With the regulator unplugged, one lead on positive battery terminal and one lead at black wire at regulator connector, I get 12.6 volts. Plug the regulator in, and check the voltage at the same spot, and I get 12.2 volts. A .4 volt difference.

I am inclined to believe now that the wiring is fine, but why would I get a different reading at the same wire with the regulator unplugged.
Click to expand...
I'm not going to try to figure out the .4 volt difference, but it's probably voltage drop through your reg.

Anyways you conventionally test for a bad ground by using the ohmmeter function of the multitester. That and visually check the battery and all other connections.

You tested the stator with the motor running? Or you did a similar method to how you tested your ground, using battery voltage? You conventionally test a stator with an ohmmeter and the plug un-plugged, you should get .6-.7 ohms between each pair of white wires.
 
I'll do some more resistance checking, there has to be something somewhere. That's why I asked where the ground wire on the harness connects to the frame. My thought is that the ground is hooked up (because I have less than 1 ohm between any metal I touch and the negative terminal), but is insufficient for the amount of current that the regulator is adding to the ground wire, hence the drop when checking that ground against the negative terminal. In a perfect system you should be able to touch any ground and have the same voltage as though you were touching the battery terminal itself, correct?

I did test the stator, but checked the resistance when the bike was off. I believe it was .5 ohms across each combination. Does the bike have to be running for this test? 10.9-11ish volts ac across each combination when the bike is running.

Full disclosure: I was a car audio guy in a past life and used these methods to check if the ground on a car was sufficient for the system they installed (as you would see lots of people run a big wire to the trunk for positive voltage but do nothing for ground). I might be overthinking the electrical system on the XS.
 
Okay, as a former audio guy you should be able to figure it out with Curly's (which I'm not really familiar with).
http://www.xs650.com/forum/showthread.php?t=10561
This is another good guide that I'm also not really familiar with.
Also, you're right, you really should be getting zero ohms continuity between battery neg and ground, I don't know where the harness grounds, just add your own jumper from battery neg to the harness somewhere if it bothers you, but I doubt that this is your problem.
 
And .5 ohms is good on the stator, and it's tested with bike off, plug un-plugged.
BTW, did the bike used to charge, or is this a new bike that you're sorting out? In the second case there's a chance that the brushes are set up wrong by a previous owner who repaired it wrong. But if it used to charge, then that's not the case.
 
It has charged, but only low to mid 13s. It's my brothers bike and he rode it that way for years. I'm going through the electrical since its in my garage and didn't appear to charge at all when we tried running it to get it here.

It looks like someone somewhere along the line repainted the frame. I found that the area where the coil and associated ground wire hooks up was painted over. I busted out the sandpaper and cleaned up the spot, as well as the logs on the coil and the frame ground wire ring itself. Voltage drop is now .2 volts between black at the regulator and the battery negative terminal.

My theory here is that if the regulator ground is less than ideal, it will be unable to ground the power coming from the green wire, and thus not be able to fully energize the rotor. My other thought is that it must pass most of the current it grounds from the green wire through the black wire on the harness instead of directly to the casing of the unit (and therefore the frame itself). If this is the case, the wiring harness to frame ground connection is critical for good charging, since battery negative goes directly to the frame. I'll run the bike this afternoon to see how it charges with that one change.
 
And... She charges at 14.1 volts at 3000 rpm. It takes forever to get there, though. It steadily climbs over 20 seconds when you hold throttle on to 14.1 and then stays there.

Is this normal or is it a slow regulator that might be failing?
 
Deeply discharged and old sulphated batteries with high internal drains can act that way.
A bad rectifier with one or two bad diodes can give sluggish charging.
A broken line in the 3-wire stator can give sluggish charging.
Probably should do the charging system tests...
 
One of the best things you can do to these bikes, in my opinion, is to mount a volt gauge where you can easily see it. If you learn to look at it when you turn the key and again when you start the bike, and occasionally while riding, you can often catch a problem before you fry a battery or are left dark.
 
I'll suggest the voltage gauge to my brother to see if he wants to go that route, but I agree that it's a good idea. I'll swap the new battery from my other bike in and see if it comes up quicker now that I know the system is capable of hitting the voltage specs.
 

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