Help with electrical/running issues

[Wahrsuul]

Ok, my brother and I were out riding yesterday - about 150+ miles. Bike ran fine for most of the run, but as we hit the slab for the last 15 miles or so to home, the bike seemed to be stuttering. At first I thought it might be wind buffeting, but once off the interstate, it was more pronounced. I managed to get it home, and left it for the evening, as I needed to get some work done on the ST. The bike was low on gas, so I figured I'd get some Techron and see if maybe I'd gotten something in the tank since I'd run it near empty. The bike started fine but ran a little rough for the 1.5 miles to the gas station. It started fine leaving the station. I rode about a mile back and stopped to take a pic of a house for sale (my brother is looking for a place). The bike acted like the battery was dead - barely turning the starter over once, then nothing. So, I managed to push the bike up the small rise, and start the coast down the hill to my house. Managed to bump start the bike, and ride into the carport. Left the bike sit for an hour or so, then got the multimeter, pulled the tank, and tried the starter. The bike fired up. Hmm...ok, checked across the battery. At idle, it was around 10.7v, and revving the engine made no difference. Shut the bike off, and the battery is around 11.7v. Try to restart it, and it acts like the battery is dead again. The connections are tight and clean.

So, have I got a bad battery, or bad alternator? If it's the alternator, where do I get a replacement?

[Gator Mike]

Many years ago my bike did the same as yours. Using a multi meter I got the same results. Replaced the alternator and all was well. I have since installed a volt meter so I can tell if it ever happens again. There are alternators on e-bay but according to our guru Carl Leo stay away from the Chinese alts. I would either have an alt. repair shop rebuild yours or buy a used one on e-bay. You might also give Carl Leo a call and see if he has one. Some time back some one on the forum spoke of a shop that would rebuild yours so that it put out more than the 35 or so amps ours put out. Maybe some one will chime in with the name. Good luck..........Gator Mike

[Mr Jensee]

Definitely a bad alternator. Check your local phone books for a repair of the existing one. Any place that can work on a car alternator can repair yours. If I remember correctly the brand is a Mitsubishi alternator. They can also increase the windings to boost to a 55watt over he 35 watt unit now. Anyway it is probably cheaper and better than ordering an original.

[triton28]

Definitely a bad alternator for sure.
Note that on a forum I read, as the output of an alternator increases due to increasing the # of windings, the cut-in RPM also increases.
At continual highway RPM this wouldn't be a problem but at low RPM urban/heavy traffic this may/could lead to longer discharge cycles for the battery without any replenishment from the alternator.
Not having tried increasing the alternator output myself, I can only refer to what I have read.
These alternators are very simple and should you wish to disassemble it yourself, using the Service Manual for reference, BE SURE when separating the 2 halves that the stator windings chassis remains with the Rr (rear) housing. It sounds backwards but the rear housing is the one that the chrome shield mounts onto with the 3, #8 hex head chrome bolts.
The rear housing must point up when disassembling the 2 halves of the alternator.
The stator assembly has 3 wire leads that go to the rectifier, mounted inside of the rear housing and these wires CAN be broken/disconnected by NOT allowing the stator windings chassis to remain with the rear housing. Sometimes the stator chassis becomes corroded and wants to remain with the front housing when one is seperating the 2 halves of the alternator, and it needs to be gently pried up, in a circular motion, off it's seat of the front housing assembly. Carefully make note of the top thrust washer placement on the rotor shaft. The rotor shaft will remain in the front housing, when removing the rear housing containing the stator windings.
It may be as simple as undercutting the Mica between the rotor's commutator copper strips and then polishing the commutator itself with 400/600 grit wet/dry sandpaper, and installing a new set of brushes.
The Manual provides checks that can be performed with a multimeter to further diagnose any problems with the alternator.
Hope that helps,
Dave

[Wahrsuul]

Thanks guys, that's pretty much what I thought. Unfortunately, Carl doesn't have any either, and the used ones he's gotten from ebay have been hit or miss, so I'm concerned about getting a used one. I've rebuilt small motors before (I have lots of vintage RC stuff), so I may take a shot at this if I can find parts.

The down side is, that the next day, the wife wanted to go for a ride. This is the 3rd time that she's wanted to go and the V has been down. With her disabilities, it's rare when she can ride, and she's annoyed that she hasn't been able to. She asked why I didn't just get her a Wing like she wanted. So, I guess after I fix the V, it'll be going in favor of a GL1800. I'd keep it, but I just don't have room for 3 bikes.

[Wahrsuul]

Ok, here's the current issue:

Rebuilt the alternator - new regulator and brushes, the slip rings looked great, so just some cleaning/polishing there. (It looks like the alternator has been opened before, so not sure what's new and what isn't) The coils had continuity, and not grounded to the case. The Alternator has 11-12 volts coming in before even starting the bike, so it should be enough to get the field going. Battery is fully charged, and the bike starts, but still doesn't seem to be putting anything out. Is there something we're missing, or is this alternator just shot and I need a new one? can't afford an oem replacement, and no one seems happy with the chinese models.

[triton28]

Did you check the diodes in the rectifier as per the service manual check procedure? There's not much else can go wrong with the alternator since you have replaced all those items.
No disrespect intended, but did you place all the insulating washers back where they came from when you reassembled the alternator?
Dave

[Chris near Kansas City]

I should have an extra working alternator that I can send to see if it fixes your problem. If it did, it wouldn't be expensive.



Regarding the GL1800, I don't have room for 3 bikes either.

[Wahrsuul]

Well, the bike is running great again. I can't say thanks enough to Chris Near Kansas City. One thing I've always appreciated about the motorcycle community is the willingness of people to help out, and Chris is an excellent example of that.

I've been riding the bike for the last few days to make sure all is well. Sadly, now I have to part with it. Wish I had room for all the bikes, but even if I did, I don't have time to ride them. If anyone is looking for a good deal on a decent bike...

[Chris near Kansas City]