1980 xs650 won't charge battery.

[OctoberNotice]

New to the site, also new to bikes. yamaha 650 is my first, had it a week now.

It runs like a top, but while idling the battery reads 11.4v, at 3-4k rpm it's only at 11.9~12.1v

I've put 100 miles on it, but once the battery dies it's DOA until another charge.

Now I've checked the fuses and most wires, all good. had to clean up the fuse box quite a bit, and now I've delved into the alternator brushes, they are two different lenghts. One is just a hair over 1/4 of an inch, and the other one being just shy of 1/2 inch.

Should I replace these and see a fix done?

Also have researched that it could be some corrosion in the regulator rectifier, where is this located?

 

[weekendrider]

The brushes are worn out. Replace and then check the voltage if it is still low check the ohms on the rotor rings.
Enjoy your new toy and welcome to the site.

 

[nj1639]

The brushes are worn out. Replace and then check the voltage if it is still low check the ohms on the rotor rings.
Enjoy your new toy and welcome to the site.

Yep, in fact check the ohms on the slip rings while you have your brushes out.....should be 5 ohms +/-

 

[OctoberNotice]

The ohms between the slip rings is a pretty solid 1.8
So my rotor is bad?

Also, the battery sat with a full charge for three days, didn't drop a hair. So that could mean there isn't a short in the wiring? Just ought to put in a new rotor and brushes? I just really want to get this charging and wiring system fixed as cheap and quickly as possible.

 

[OctoberNotice]

Oh also, there are a couple of the rotors on ebay used, says they read 5.5-5.6 ohms for $60.
If the ohms read good like that are they pretty much safe to buy? Where do I go for a safe buy, but still affordable?

 

[Grinder]

If your bike has the TCI electronic ignition you have to get a rotor from the later year bikes. The later years have a small magnet imbedded in the rotor to trigger the ignition where the points ignition rotors do not. This magnet can be bad(weak) as well so be careful. Take the small chrome cover off above the left spark plug and see what's in there. If it's empty you would have the TCI as that's where the points would be on the early bikes. Custom Rewind is the best place to get a rotor from what people say.

 

[XSLeo]

Call 1-800-798-7282 talk to Gary. Last I checked a rotor rewind was $125 + S&H. Might be more now. Send him yours and he rewinds it to better than new. the technology has improved in the last 30+ years.
Leo

 

[nj1639]

Choosing between a rewind or one that is at the least 28 years old, I'd go for the rewind for peace of mind.
My '83 ohmed out about the same as yours when I first got it 5 years ago. I shopped around and found a rewind service that sent me the puller and accepted two dead rotors for a reduced price on one rewind.....75 bucks.

 

[OctoberNotice]

So, I'll have the new alternator brushes coming in next week, but to clarify; I'm pretty new to this, what's the difference between the stator and the rotor?

With my rotor reading only 1 ohm between the slip rings, i just specifically need a new rotor to replace it, or a rebuild "rewinded" one?

 

[nj1639]

You take the stator off to get to the rotor. As far as a replacement for the rotor- your call. I saw where Hughs Handbuilt was selling some used ones quite resonable. You'll need one with the small magnet inbedded.

 

[swbill]

And be warned many of the aftermarket rotors have a week magnet and won't work. I'm dealing with one right now. Waiting to hear from the supplier to find out if there going to take care of the problem. Wish I would have went with a rewind instead.

 

[OctoberNotice]

I'm gonna go with a rewind on my rotor.

I know it's hard telling, but after I replaced the alternator brushes and rewind the rotor, do you think my charging system will be in order?

I'm going to get a new fuse box and clean up the wires a little more yet.
I wanna get this fixed up to pack some miles on it then I'm thinking of wrapping the exhaust and redoing the handlebars.

Here is the bike BTW

 

[Dennis]

Magnet on the rotor is a really cheap and easy fix.
I got a rotor from Gary and after about 6 months I traced a problem back to the magnet.
I didnt bother asking for another as it only cost just over a buck to fix

 

[OctoberNotice]

The magnet on the rotor?

How much am I looking at to get a new rotor or rewinding or magnet from gary or custom rewind?

 

[Dennis]

Gary is Custom Rewind
You are looking at about 130 with the core of the old rotor
1 yr warrenty but I dont know if that covers the magnet.
The magnet is only needed for the later models useing the TCI

 

[xjwmx]

I saw where Hughs Handbuilt was selling some used ones quite resonable.

I saw that too. But a long time ago I read here where Hugh was just pulling them off without the proper tool, the main thought being PMA conversions, and maybe the ones that still work are ready to read 1 ohm in the near future themselves. Maybe he removes them more carefully now?