Alternator Service Recommendations

[Wagner73]

I'd like some servicing recommendations from all the learned folks that have been there, done that.

Initially pulled the cover as I suspected a po had jammed an 18T sprocket in there, and that turned out to be correct. Gonna fix that

But since I have the cover off, etc., are there any preventative things I should do to stator, rotor, brushes, etc. to obtain as close to "like new" performance as possible? Bike is a 78E with ~6K showing on the clock. Cheers.

 

[Kevin Kruse]

From what I've read the stators are bulletproof, the rotor windings however are known to fail if ran for periods of time with bad/dead battery (overheats the rotor windings). My rotor wasn't charging and got it rewound by Jim here on the forum (recommended not to buy aftermarket rotor), but if it's measuring good ohms between rings then you should be fine. And brushes have a wear limit.

https://www.xs650.com/threads/1978-xs650-special-project.65053/post-812229

Also can be a good idea to replace the stock regulator/rectifier with an upgraded/modern replacement.

https://www.xs650.com/threads/diy-reg-rec-5twins-and-jim.55842/

 

[gggGary]

That ring looks good, there SHOULD be some carbon transfer on the ring, it's how carbon brush slip rings are designed to work.
Check brush lengths, anywhere near the brush limit line is replacement time. Ohm out the rotor, 5.3 to 6.0 ohms, are the usual precautions. The rotor varnish should be a caramel color and smooth, black and bubbly varnish, (heat) is a sign of insulation breakdown and imminent failure.

Like KK sez running with a bad battery really stresses the alternator.
Many of us believe in a voltmeter placed up on the bars.

 

[Its been a long time]

Another vote for visual and electrical checks. Change brushes, check all wiring and joints, fit modern rectifier and regulator. As good as it gets.

 

[Wagner73]

Exactly what I was looking for, including the linked info...many thanks!!

 

[Jim]

https://www.xs650.com/threads/rewound-alternator-rotor.54276/

 

[Wagner73]

Thank you. Yes I have seen your listing in the Classifieds, and will definitely go your way if the rotor doesn't check out to spec (or looks burnt per Gary's pic). Cheers.

 

[Wagner73]

Or would you recommend a rebuild/rewind just to be on the safe side since it's ancient?

 

[Jim]

Or would you recommend a rebuild/rewind just to be on the safe side since it's ancient?

They're pushing 50yrs old. It's a question of when... not if.

 

[Kevin Kruse]

In the meantime, a visible voltmeter might be a good idea to be able to see if anything is acting up, might save you getting stranded somewhere. Mine stranded me..

 

[Wagner73]

So @Jim will rebuild/rewind my rotor.

Two additional questions related to the stator: 1) Should I do anything with it i.e. cleaning, etc., and; 2) For reinstallation I see mention of an alignment pin. I am apparently not looking in the right place as I haven't discovered it yet, so any additional info, tips, etc regarding reassembly would be appreciated. Thanks.

 

[gggGary]

Stators are pretty "bullet proof" check wiring bundles for cracks etc.
EXTREMELY important note all the screw lengths and locations if removing brush block, pickups etc. the wrong screw in the wrong place will destroy a slip ring has happened to many.

 

[Wagner73]

Thank you for the pic of the pin, etc - guess I just have to get on my belly and open my eyes!

But no specific cleaning, etc.?

I have purchased NOS brushes and will install at the same time as rotor reinstallation. Thanks again.

 

[gggGary]

Unless it's filthy oil coated I'd leave it alone.
If it is REALLY gunked up, mineral spirits with a squirt bottle, blow off with compressed air, no scrubbing on stator coils.

 

[Its been a long time]

Thank you for the pic of the pin, etc - guess I just have to get on my belly and open my eyes!

But no specific cleaning, etc.?

I have purchased NOS brushes and will install at the same time as rotor reinstallation. Thanks again.

I trod the same path as you about 18 months ago. It goes a little against the grain, but the advice is not to clean the stator unless it's extremely dirty. And I didn't. I blew the loose dust away and left it at that. With a rewound rotor, that's going to be as good as it gets.

 

[Wagner73]

Ok, will do. Many thanks.

 

[Jim]

Some mineral spirits and a soft-ish bristle brush does a fine job cleaning up the stator.
I've tried every chemical solvent known that's commercially available to use for us backyard guys to soften the finish on the rotors.... nothing works except a hammer, chisel and bead blaster. I've even tried various paint strippers.

The stator is coated with the same finish. You'll not hurt it with anything in your standard equipment shop.
Don't use anything water based as there's surely a crack(s) in the insulation after this many years. Don't want to give corrosion a leg up, eh?
Whatever you use, blow it dry with shop air after it's clean.