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Discussion Starter #1
Here's a new problem for me and after 225k miles I've had most of the common ones! :(

The last three times I started the bike I noticed that the voltage output doesn't jump right up to 13.5v like it used to. Now is stays around 11v for 15 seconds before it suddenly jumps up.

I'm no mechanic but could this be a stuck voltage regulator and if so, where can I find it?

Thanks in advance...

Cheers!
 

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The regulator is in the alternator. Did you mean 225,000 miles on the bike?

If so, you probably have badly worn down slip rings on the alternator rotor. the exicitation current for the rotor goes through two brushes in the regulator that ride on the slip ring. One slip ring wears much faster than the other for some reason. Maybe reverse "plating' of the copper due to electrolysis.

If you pull the alternator and want to replace the slip ring assembly, I have a link to a site that sells that.
 

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Forgot, there is one other somewhat common alternator problem with the LT. The small wire from the dash alternator light sometimes works loose, and does not always make good contact. The current through the light is the exicitation current for the rotor. Check that the bulb lights when you turn on the ignition, before you start the engine. If it does not, the alternator may or may not start charging, depending if there is enough residual magnetism in the rotor to kick start it. The exicitation voltage to the rotor is the "bootstrap" to get it going, then the charge voltage produced by the alternator takes over, turning off the light.
 

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Discussion Starter #4
dshealey said:
The regulator is in the alternator. Did you mean 225,000 miles on the bike?
You betcha! ;) I'm trying to beat Don Arthur's record of 305k miles.

dshealey said:
If you pull the alternator and want to replace the slip ring assembly, I have a link to a site that sells that.
I have the alternator from my original motor with 175k miles. I would like the link you mentioned so I can price a rebuild and compare that with a low mileage used or new one. Should anything else be changed inside the alternator other than the slip ring?

Thanks again David! Long time no see and now that you're in TN it's likely to be even longer... unless we have another reunion in Gatlinburg!

Cheers!
 

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ltcommuter said:
You betcha! ;) I'm trying to beat Don Arthur's record of 305k miles.

I have the alternator from my original motor with 175k miles. I would like the link you mentioned so I can price a rebuild and compare that with a low mileage used or new one. Should anything else be changed inside the alternator other than the slip ring?

Thanks again David! Long time no see and now that you're in TN it's likely to be even longer... unless we have another reunion in Gatlinburg!

Cheers!
Here ya go Bob:
http://www.wagneralt.com/
Click on 'Product Lines'
Then click 'Product Catalogs'
Then 'Slip Rings'
It is slip ring assembly W160-02

They are in Chino, CA, not far from you.

The alternator/brush assembly is probably available there too, but I never looked it up. The Bosch part number is 1-197-311-542
 

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I've found that, until I take the revs up to about 3000rpm, my bike stays at 11.5 - 12.0 vdc. Once I rev it up near 3000 rpm, it jumps and stays above 12.0 vdc no matter what revs are hit - even at idle.

I thought this was normal for the bike. Isn't it?
 

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Discussion Starter #7
dshealey said:
Here ya go Bob:
http://www.wagneralt.com/
Click on 'Product Lines'
Then click 'Product Catalogs'
Then 'Slip Rings'
It is slip ring assembly W160-02

They are in Chino, CA, not far from you.

The alternator/brush assembly is probably available there too, but I never looked it up. The Bosch part number is 1-197-311-542
Thanks David. Part was in stock and will be here Thursday!

Is there anything special I need to know to swap it out?

Also, you didn't mention anything else in there that should be cleaned or replaced to insure the regulator is working properly. Is the slip ring all there is to this?

Cheers!
 

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Discussion Starter #8
Buckelew said:
I've found that, until I take the revs up to about 3000rpm, my bike stays at 11.5 - 12.0 vdc. Once I rev it up near 3000 rpm, it jumps and stays above 12.0 vdc no matter what revs are hit - even at idle.

I thought this was normal for the bike. Isn't it?
Mark - Good to hear from you!

My experience has been that there is a relationship between low end revs and voltage but in my case the voltage wasn't varying at all when the cold engine is started or reved. Then after a few seconds it jumps to "normal" output. That's why I suspected the regulator. It is almost as though it's sticking. Can solid state do that? I dunno.

Cheers!
 

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ltcommuter said:
Mark - Good to hear from you!

My experience has been that there is a relationship between low end revs and voltage but in my case the voltage wasn't varying at all when the cold engine is started or reved. Then after a few seconds it jumps to "normal" output. That's why I suspected the regulator. It is almost as though it's sticking. Can solid state do that? I dunno.

Cheers!
Hey Bob. I noticed this when I installed my GPS - after the generator shaft breaking, I figured that it would be handy to have the GPS unit display the bike voltage. The actual point, at which the voltage jumps and stays higher, is about 2800 rpms. Up until that point, the voltage stays low. I'll have to try leaving it and see how long it takes to "jump" up without touching the gas.

oh, well. Nice to see you.

I'm commuting from SJ to Alameda now. If you see a crazy guy on 880, on a red Ducati Hypermotard with a blue/black jacket - that's me.
 

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ltcommuter said:
Thanks David. Part was in stock and will be here Thursday!

Is there anything special I need to know to swap it out?

Also, you didn't mention anything else in there that should be cleaned or replaced to insure the regulator is working properly. Is the slip ring all there is to this?

Cheers!
You have to pull the bearing off to pull the slip ring assembly off. I was going to order one to rebuild an alternator I have, but crashed the bike before doing it. I THINK you have to cut the little 'flags' that the rotor wires are welded to on the old slip rings and solder these to the new flags on the back of the new slip rings. I could see no other way to attach the wires. You sure do not want to cut them, as they would no longer be long enough to fasten to the new assembly. This will be pretty evident once you get the alternator apart.

I would probably replace the bearings, and check the length of the brushes in the regulator, because the brushes are not replaceable themselves I don't believe. If requires a new regulator assembly if the brushes are worn down too much.

When you replace the slip ring assembly you may want to have someone with a lathe, or an alternator shop, check that the slip ring surfaces are running true to the bearings. If not, turn them for no runout.
 

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Discussion Starter #11
dshealey said:
...pull the bearing off to pull the slip ring assembly off....cut the little 'flags' that the rotor wires are welded to on the old slip rings and solder these to the new flags on the back of the new slip rings...replace the bearings, and check the length of the brushes in the regulator, because the brushes are not replaceable ...it requires a new regulator assembly...have someone with a lathe, or an alternator shop, check that the slip ring surfaces are running true to the bearings. If not, turn them for no runout.
Holy sh*t, Batbykeman! Just shoot me now! :eek:

This puppy is going to the alternator shop with the slip ring that I already ordered to get completely rebuilt by someone who knows what they're doing. That wouldn't be me. :p

Cheers!
 
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