Crazy electrical problem

[blivy]

Hey everyone. Brand new to this site.
I'm fairly new to bike mechanics too (I just rebuilt a cx500 for myself and am now helping my buddy with his 1978 XS650).

About his bike--1978, great condition. He's owned and serviced it regularly for the last 10 years. However, he doesn't do the work on it himself  (he and I are trying to learn together).
His bike started dying on him earlier this month. Last week I went to check it out with him. When it ran, it ran beautifully. But then at what seemed like random times would sputter then die. Once it died, it would be very difficult to restart.
Fuel was new and fine. Air filters were clean. Spark plugs looked good and gap was correct (though can't remember the spec offhand). Battery tested at (if i remember correctly) 12.8 volts.

Then during one of the times when we got it started again I started testing out the controls and found that whenever I turned the blinker on, the bike's idle would change (drop and become unsteady) and then the bike would die shortly thereafter.

I don't know much about these bikes--any ideas of what this might be or a sequence of what to check out next (and how to do so)?

Thanks for the help.
-blivy

[XS Rod]

Welcome to the forum...
Generator brushes is the first thing coming to my mind...

[blivy]

Thanks. Is there a good site or resource where I can learn how to replace these?
(given that I'm assuming worn brushes have to be replaced....)

[XS Rod]

You should look around the site... an online version of the shop manual is available for free... Personally I own several.
You can inspect the brushes by removing them ... they have a minimum dimension line engraved in them as I recall. They are located on the LH side of the engine under that little round cover. Remove the two screws and your looking at the brush holders... brushes are hidden, they contact the alternator on those little clean paths you see on the face of the alternator...
If they meet the minimum length requirement, you need to troubleshoot your electrical system... and not randomly start replacing parts.
PS this post will prolly be relocated to electrical...

[blivy]

Thanks for the advice. 
I'll get with my bud and see if we can figure this out.