Did Curly's check, still can't figure it out

[AdvSwede]

OK, I know that this topic has been beaten to dead. I have read posts and went through Curly's check list and still am not sure what the problem is.

1983 Heritage Special

At 3,000 rpm I get a little bump in voltage at the battery up to 12.6 to 12.75

Did the feeler guage check with the grounded green wire. No movement in feeler guage. I have to admit I don't really understand if I need to unplug the connector or ground it from behind and which connector, two have green wires.

the three fabric wires coming from the Stator show 10v AC. The resistance wire to wire it was .7 ohms. Wire to ground is 23.7 ohms ( to low??)

The rotor is 7 ohms ring to ring and infinate ring to ground

So, is it the Stator?

 

[gggGary]

Have you checked the brushes? Always do this when it isn't charging. to check the stator wires the yellow wire should be unplugged it is in the same bundle as the three whites but has a separate single plug connector. With the yellow unplugged the white stator wires should be infinite (no meter movement) to ground. The 6 connector plug with the white wires should be unplugged also

 

[AdvSwede]

I did check the brushes. They were with in spec. I will unplug the yellow wire and check the white wires again

Unplugged the yellow and the resistance of the white wires to ground is now infinate. Wire to wire is .8 ohms

 

[gggGary]

Good that you checked brushes, if they are near the wear limit of 7mm replace them. For me I think anything less than 10mm is replacement time.
Your stator sounds good.
On green wires; there is one green wire for the brush that gets grounded by the voltage regulator, there is a blue wire in the plug also, that wire is the neutral switch wire.

This is not perfect but expands on the curly's guide a bit with some detailed pics.
http://www.xs650.com/forum/showthread.php?t=10561
the slap test should be done with everything assembled, the metal item should move when you turn on the ignition with everything hooked up. To do the "short the green wire test" everything should be hooked up you can short it right at the brush with a short jumper (this test is for late model only, like your bike Advswede) a short U of wire to short the green brush holder to the stator frame will work fine. The green wire goes to the top brush on the late model bikes. I have to check the book but I think 10 volt AC is very low for the white wires. that test would be done engine running with all the connectors plugged in. Are the basics done? fully charged battery that has passed a load test, ground wire connections checked? That tech thread also shows the diode check in the regulator. how does that test do on your bike?

 

[AdvSwede]

Checked battery it was at 12.2 volts, it is brand new, placed it on the charger. I grounded the top brush and did the slap test, The main fuse blew.

 

[AdvSwede]

gggGary, thanks.

The battery is brand new. The voltage is a little low (12.2v) I placed on the trickle charger. I did the slap test with everything hooked up. When I turned the key on I blew the main fuse, twice. No more fuses. Could there be a short in the Stator/Rectifier wiring? Is there a typical contact area where the insulation on the wiring wears?

 

[nj1639]

I've seen stator wire wear where the wiring routes from the stator up to the connecting block.....from the wiring exit of the ....we'll say alternator housing.... to up and around the chain/front sprocket area.

 

[retiredgentleman]

gggGary, thanks.

The battery is brand new. The voltage is a little low (12.2v) I placed on the trickle charger. I did the slap test with everything hooked up. When I turned the key on I blew the main fuse, twice. No more fuses. Could there be a short in the Stator/Rectifier wiring? Is there a typical contact area where the insulation on the wiring wears?

A few things to try. Unplug the reg/rec connector. Remove both brushes. Make sure the brush wires are not touching alternator frame. Now turn on the key, fuse should not blow. Confirm that you have 12 volts at the brush brown wire. Turn key off. Re-connect the brush for the brown wire. Key on, fuse should not blow. Key off. Re-connect the brush for the green wire. Key on, fuse should not blow. Key off. Ground the green wire brush. Key on, fuse should not blow and a feeler gauge should be pulled over to the rotor indicating a strong magnetic field.

 

[gggGary]

I would like it if we could see a picture of your brush assembly?

 

[AdvSwede]

Thanks for all the advice. I'll rip into it tonight. I'll post some pics so everyone can get their "Pix Fix". I'll post later

 

[AdvSwede]

Pics of the alternator and ground jumper

 

[AdvSwede]

OK, had time to think of the trouble shooting that I did yesterday. The fuse blew cause I did not disconnect the trickle charger before I did the ground wire test. I really didn't think that would have put out enough amps to do anything. Well, lesson learned.

I installed new fuse and did the ground test. The magnetic field is there it does draw the .015" feeler guage toward the stator. It actually draws with or with out the ground. I replaced the cover and tried again. There was not enough magnetic field to draw the .015" feeler guage.

I guess it is the rotor??? Would the 7 ohms resistance on the rings of the rotor be an issue, should I clean the rings?


With battery fully charged I now get 9.9 volts AC at idle from the stator. A little increase in rpm and it goes to 10.8. Idle is at about 850 rpm (low?)

At 3000 rpm I get 13.7 volts DC at the battery

 

[gggGary]

I have been watching, advswede. I need to test a thing or two to be sure, but just off the top of my head the AC reading seems a bit low. The 7 ohm reading on the rotor is a tad high but meters are notoriously inaccurate at low ohms readings. Rotors typically fail as the wire insulation breaks down and loops short out ie they will read 4.5 ohms on down.
An XS650 will not charge at 850 RPM that is part of the reason Yamaha calls for a 1200 RPM idle, so it doesn't kill it's own battery. BUT you are showing a reasonable charge rate at 3K so I wonder if maybe you just have some crappy corroded wires/connections hanging around. The fuse boxes are notorious for falling apart and the ground strap up at the battery has been found rotted many times.
Oh; does your head light come on as soon as you fire it up? With stock wiring that is the basic "charging system is working" check. The yellow wire from the stator goes to a relay that closes the headlight circuit. If the stator isn't generating the headlight will not light.

 

[AdvSwede]

" a short U of wire to short the green brush holder to the stator frame will work fine. The green wire goes to the top brush on the late model bikes."


I reviewed the link and noticed that the wire connections to the brushes was a little different than my bike. On my bike the green wire is on the bottom (outside ring) not the top (inside ring). Should I be grounding the lower wire not the top?

Update:

I rechecked the voltage at the brown wire(+) to the brushes. It is 11.7v, battery is 12.5v. According to link, .3 volt drop is the max. I will check the switch and go from there.

 

[AdvSwede]

gggGary,

I didn't catch your previous post, sorry. The lights come on. I installed new battery cables from MikesXS. I will go through the wiring and see what I get. I guess I also have to set the idle.

Thanks for your help so far.

 

[gggGary]

Yes my bad, ground the brush with the green wire. And also yes, key switches with high resistance are common too. They can be taken apart, cleaned and reassembled. As a check a U shaped 12 gauge house wire with the ends flattened with a hammer will bypass the ignition switch at the headlight housing connecter, connect the red and brown wires, ignore the blue wire, an easy trouble shooting item.

 

[retiredgentleman]

I did check the brushes. They were with in spec. I will unplug the yellow wire and check the white wires again

Unplugged the yellow and the resistance of the white wires to ground is now infinate. Wire to wire is .8 ohms

You say you have 0.8 ohms white to white wires. What does your ohmmeter read when you touch the two test leads together?

With the engine idling at 1200 rpm (connectors connected as normal), you should measure 12.5 to 13 volts AC between any 2 of the white wires.

 

[AdvSwede]

OK, checked volts at ignition switch plug, it was at battery voltage. The positive brush at the alternator is close to .9 volts below battery voltage. With the air box in the frame it is difficult to trace the brown wire from the ignition switch. Does the brown wire pass through one of the two connectors that are behind the air box on the left side of the bike???

To confirm this (Brown wire) is the issue could I run a jumper from the battery (+ terminal) to the positive brush?

 

[AdvSwede]

You say you have 0.8 ohms white to white wires. What does your ohmmeter read when you touch the two test leads together?

With the engine idling at 1200 rpm (connectors connected as normal), you should measure 12.5 to 13 volts AC between any 2 of the white wires.

not there, I have a contradicting info regarding this. I have checked the resistance with two different meters.

 

[XSLeo]

Yes try that. That will bypass the wires in the harness.
On very low ohm readings you need to touch the probes together to get a reading of the probes, then subtract this reading from the rotor and stator ohms readings. As in touch the probes and get say .3 ohms. Then yiou test your stator and get say 1.2 ohms. 1.2 - .3 = .9, or rotor of 4.5 - .3 = 4.2.
The 7 ohms on the rotor could be the trouble. I have a rotor that reads 5 ohms at room temp. As the engine runs it charges good, untill it gets warmed up as the rotor gets warmer the ohms reach 8.5 at operating temps. With my on board volt meter the battery votage slowly drops as the rotor gets warmer. Replaced with one that reads 5 ohms at all temps, now charges well. With your 7 ohms at room temps could be why you have low output.
The higher the ohms the less current going through the rotor, lower current flow means a weaker magnetic feild created by the rotor, less magnet = less output.
If you have a spare rotor that checks closer to 5 ohms try that.
Leo