Another charging system nightmare

If it's broken or just needs tweaked

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justin2278
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Joined: Sat Jun 16, 2007 10:44 am
Location: Cincy

Another charging system nightmare

Postby justin2278 » Sat Jun 23, 2007 2:34 pm

Hello all,

Just got my 1980 cb650 custom about 2 weeks ago. Bought it with a charging problem. The first thing I did was download the flow chart off of the link on Dave's Ultimate Guide. Through that I found that my rotor was only giving me about 1 ohm of resistance, so I got another rotor. Tested good when I first checked it (I think). Put it in, still had a problem, although my meter said 13.5 volts at the battery when I first tested it. So I thought it was the battery, got a new one, thought it was fixed. Went for about a 15 min ride and realized I still had a charging problem. Tested the charge at the battery and the meter would kind of jump up here and there, telling me that it is getting some kind of charge... right? So upon inspection of the rotor again, I noticed that somehow the stator is actually rubbing on the rotor. The coating on the outside of the rotor was rubbed off to bare metal. And now my new rotor is only showing 1 ohm of resistance, that was a perfect waste of $90. Any ideas why the stator would be rubbing the rotor or why my rotor went bad. :x

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holysmokes
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Location: nova scotia

Postby holysmokes » Sat Jun 23, 2007 4:17 pm

the stator windings are loose?

is the rotor touching all the way around, or is it wobbling

justin2278
Posts: 12
Joined: Sat Jun 16, 2007 10:44 am
Location: Cincy

Postby justin2278 » Sat Jun 23, 2007 4:27 pm

The rotor seems to be touching all the way around because the scratches go all the way around. Visually, the stator seems to be intact.

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Volker_P
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Postby Volker_P » Mon Jun 25, 2007 1:23 am

Welcome here! :D
Well, thats no good story. If scratches go all way round at the rotor, how does the stator look like? One scratched location would mean it might just not centered, two opposite scratched regions would mean it is not circular any more (has been compressed somehow). The left engine cover carrying the stator should have (hollow) dowel pins for exact positioning at two bolts. Possibly they are missing?
As the rotor windings are quite protected in the steel housing, I would guess it might be still allright. I'd rather be concerned that the stator could be damaged now. Some pictures may help to get an idea.
Resistances in the order of 1 Ohm are hard to measure with a cheap multimeter, so don't give too much on the reading. What do you mean with
...the meter would kind of jump up here and there...
Is it a digital meter? Did values fall significantly below 12V? It sounds a bit like a regulator (or cabling to there) problem. Did your first battery lack significantly of liquid?

justin2278
Posts: 12
Joined: Sat Jun 16, 2007 10:44 am
Location: Cincy

Postby justin2278 » Mon Jun 25, 2007 8:14 pm

Thanks for the welcome Volker P! Glad to hear some feedback. Alright, I think I'm getting some where. Went and bought a digital tester because I just don't trust the old analog. I'm definitely not getting a charge now. I think maybe the "jumping around" was the old tester going haywire, or maybe it was picking up my "negativity"lol. Anyway my new rotor has got basically no resistance at all. I know it did before. Her's my theory. The engine cover is missing one of the dowel pins causing it not to be lined up properly, therefore causing the stator to rub the rotor, causing the rotor to heat up, causing the rotor to fail. Do you know what kind of clearance there is between the rotor and stator? It seems that the rubbing is on the top of the assembly, because that is where the stator is rubbed. Do you think the rubbing could have damaged my stator? It doesn't seem to be too mangled. Do you think I could get that dowel pin anywhere? I'm trying to get some pics up now. Thanks in advance for your help.[/img]

justin2278
Posts: 12
Joined: Sat Jun 16, 2007 10:44 am
Location: Cincy

Postby justin2278 » Mon Jun 25, 2007 9:10 pm

I have no idea of this will work, but here goes nothing.
<a><img></a>
<a><img></a>[/img]

justin2278
Posts: 12
Joined: Sat Jun 16, 2007 10:44 am
Location: Cincy

Postby justin2278 » Mon Jun 25, 2007 9:12 pm


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Volker_P
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Postby Volker_P » Tue Jun 26, 2007 1:48 am

Helpful pics! :) I do not know the gap size but a low clearance helps to increase generator performance (avoids field losses). The design obviously needs these dowel pins. Maybe you know someone with a turning lathe who can make a copy of the one you still have.
Rotor looks suspicious, maybe the insulation was softened and cables found contact by centrifugal forces.
The stator windings look allright, however the insulation between yoke plates may be damaged. Should work anyway with minor losses if this is the only damage.

But before you go to spend money again I would recommend to check the whole charging system. My suspicion is that the dowel pin got lost during the efforts of the previous owner who concentrated on the rotor and stator only but failed to get it fixed. Might be a cable problem, also have a look on the brush holder and the regulator.
Tests for stator and regulator are described in the online manual: http://cosky1.tripod.com/ (cosky0 provides the rest of the manual).
Besides of possible negative karma, the jumping of your old voltmeter may origin from a defective regulator. The digital ones are usually a bit more sluggish which sometimes is irritating even more. I have one but I prefer my old (looking like about 1960's) one which once even survived a short that blew out a 10A(220V) fuse. :lol:
Good luck!

justin2278
Posts: 12
Joined: Sat Jun 16, 2007 10:44 am
Location: Cincy

Postby justin2278 » Wed Jun 27, 2007 3:16 pm

Well, I know that rotor is shot, so I have another one, but it's not going in until I find a dowel pin for the cover. Once that goes in, I'll be able to trace the problem somewhere else if that's the case. I'll keep you updated.


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