81 heritage not charging

AceofSpades

AceofSpades

XS650 Addict
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Hey everyone,
I just picked up an 81 Heritage Special. Got it really cheap, and now I know why.
The PO claimed (but had no proof) that he had the alternator rebuilt before having idle problems. Well, I pulled it out of his barn, got it home and started looking things over.Everything looked pretty much stock, if not original. Took a chance, dropped in a good hot battery, and poured in a half gallon of Marathon's best, and it started up and settled right into a smooth idle. The first test ride was limited to about 3 miles, all good!
Second ride was about 16 miles, with multiple stops (engine off) and still all seemed good.. Hell, even the OEM horn still worked!
Yesterday, I decided to ride it to work (I work evenings) about 7 miles one way. I had a couple minor diversions, but by the time I got to work, the turn signals, horn, and lights were fading... and the engine started running rougher... by the time I got to work, the battery was dead, and I had almost no light at all. I swapped in another hot battery, and it rode home (in the dark) just fine, and everything worked perfectly...

So I am looking for most likely culprits to a charging issue. I hope I can get it straighted out for very little cash outlay... I know things can get pretty expensive trying to save a stock charging system. I have a regulator and a rectifier off another 81 (unknown condition) how can I test these pieces? Could it be corrosion in the alternator itself? just a fuse?

I have a clymer, and I have to refer to it, I am sure.... but thought I would get some opinions from those that actually deal with these machines on a regular basis.

I plan on testing today, to see if it is charging at all, I have about a week to get this thing right... help me, please.....
 
Start by testing, and check the brushes. The curlys charging guide lays it all out, follow that, then if you have any questions post back? Good luck, but these charging systems aren't all that complicated as long as you don't just start throwing random parts at it creating more problems, before you fix the first problem. Hint; reg/rec is about 4th on the list of likely culprits.

Here's a link to a Curly's with some follow on pics and details as found in the XS650 tech section.
 
search for:

electrex guide
mike nixons guide

online. they are good starts for troubleshooting

also: oregon motorcycle parts has a good guide for fixing connections (and they have good aftermarket regulators)

and, I've got several other guides I can email you - they are for honda, but still a good start for yamaha.
 
ok, tried the "SLAP TEST". when I first turned the key on, I got nothing... bumped the starter button, and tried again.. and it repeatedly passed the slap test... where to go from here?
 
#1 pull and check the brushes, they are about a 5,000 mile wear item. $10 you are back in business (if that's it) always nice to clean up the rings on the rotor.
 
ok, brushes are approx. 8mm and the slide rings are clean... started bike and (with idle up to 1300) it is charging pretty consistantly at 12.8-13.2v.... is it possible that my first battery was just no good?
 
possible, I think 8mm is on the short side for the brushes, get new ones anyways. Note the oddball "wrap the wire around the holder" design. The brush and little plastic rectangle only fit in the holder one way. A volt meter is a nice gauge, you can find a cheapo cigarette lighter volt meter hack it and wire it to the brown wire from the ignition switch in the headlight housing then you will know what's going on.
 
I will just add, pay close attention to what hole the different sized screws go into on the brush assembly. I didn't and put a long one in a short hole. It touched the rotor, shorted out at the system which resulted in releasing some smoke from the electrical under the seat as well was destroy my expensive Reg/Rect combo. Lesson learned. :banghead:

~ Derek
 
wear limit is 7mm I would replace brushes that were at 8mm, new is 14.5mm I have had erratic charging from brushes longer than 8mm. While you are there measure across the slip rings on the rotor, should be in the 5.6 ohm range anything below 5 is in not so good territory.
Yes like Derek says stators, wire clamps, brush holders use several length screws, right screw, wrong place get$ ugly very fa$t
 
Gotcha! I rode it to work again today, and when I got home I checked battery voltage, it was at 12.83v..... I will be getting new brushes, as soon as I figure out the best source, and get paid this Thursday.
 
12.83 is good for after the ride, it's probably charging. check where the voltage tops out at (IE: should be a MIN of 13.8 volts and 14.5-14.7 volts is best). go through and clean all your connections and use dilectric grease on them.
 
A voltmeter is a must have IMO. It's a great thing to see what the health of the charging system is in and gives you a heads up before any slow drain failures.

Later that day.......
Picked up a voltmeter for my 77D at Orschliens, Tractor Supply was out of them. ....under 20 bucks.....same kind I have on my '83. Thanks for the prod.
 
Last edited:
so where is the best place to get the replacement brushes? the local Yamaha dealership wants $45 PER BRUSH!!!!!!! I seen that Mikes has them for about $20, plus the ridiculous shipping charges... and I found one place on eBay for $14.99 a set... any other sources? I would much prefer to buy from someone like Hugh... someone that is trying to help out hobby grow, not get rich off of us.
 
AceofSpades said:
so where is the best place to get the replacement brushes? the local Yamaha dealership wants $45 PER BRUSH!!!!!!! I seen that Mikes has them for about $20, plus the ridiculous shipping charges... and I found one place on eBay for $14.99 a set... any other sources? I would much prefer to buy from someone like Hugh... someone that is trying to help out hobby grow, not get rich off of us.
Click to expand...

Give Hugh a call and ask, he seems like a friendly bloke.

I think when I ordered mine I got them from Mike's. Twas a while ago.

~ Derek
 
MikesXS

Alternator Brush Set

24-2651.jpg

Alternator Brush Set - Fits: 1980-84 XS650. Complete set as shown. Replace brushes if carbon brush is 7mm. (0.276") or less. Note: To install pull brush assembly around to opposite side of metal bracket its soldered to and then insert into holder.
OEM Reference #
• 256-81612-11-00


Part #24-2651
$16.50 USD Set



There's always more you need, sump filter, gaskets, etc. It seems I seldom have a problem hitting $150 but I do stock many common items....
It would be nice if they would use the post office for small stuff.
 
Derek said:
I will just add, pay close attention to what hole the different sized screws go into on the brush assembly. I didn't and put a long one in a short hole. It touched the rotor, shorted out at the system which resulted in releasing some smoke from the electrical under the seat as well was destroy my expensive Reg/Rect combo. Lesson learned. :banghead:

~ Derek
Click to expand...

How do you make sure you have the right screw for the right hole? Someone else removed the screws from mine and put them in a screw tray. Now I'm freaked out, don't want to burn my Reg/Rec!
 

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