No headlight Not charging

[Spike]

What's up guys,

So here's the story (there's always a story):
I have a basically stock (electrically anyway) '79 XS650.
Last year, I decided to be a "genius" and switch to an H4 bulb (low amp 50/55). I think due to the constant vibration inside the headlamp housing (aftermarket) the bulbs continuously burnt out. I would replace them (monthly) and everything would be fine, but eventually, I lost power to the headlamp circuit completely. After trying several known good bulbs, I had no power at all to my headlight socket. I checked voltage with a fluke meter on the yellow and brown? (can't remember color?) wires and had nothing.

Around that same time, I made a very impatient and stupid decision to hard wire another bulb straight from the battery (fused) to an H4 bulb as a temporary patch so I could ride at night. This lasted a couple days but completely drained the battery after enough time.

Now, i've discovered the alternator isn't charging, on top of the old headlight problem. When people say, "you'll blow your charging system" (which is what i'm assuming I did) what exactly does this mean? Have I fried the reg/rec or the stator and/or rotor?

Just looking for any input on what I should start testing next? I've started with checking the voltage at the battery (fully charged) 1200 to 2000 rpm, and I have no charge. I tried the slap test and have no sign of power from the rotor.

Any ideas guys? I really appreciate any feedback or input from anyone.

Thanks for listening.

 

[gggGary]

Sounds to me like your constantly burning out headlight bulbs could have been auto bulbs not up to the vibration like you said OR was a symptom of a charging system that was putting out too much voltage. So there was the first problem. Instead of finding and correcting the first problem you treated a symptom. Now something else in the charging system has failed, stopping it from putting out ANY current. By design the head light is powered through a relay that depends on the alternator working. So when the light doesn't light your alternator is kaput. SO you now you may need to find TWO faults in the charging system.

For the first problem, overcharging, carefully check all your electrical connections ESPECIALLY grounds, ground wires, bolted connections to frame, engine, battery etc. Also check the voltage regulator, in 79 it's an old style mechanical points unit, the points can stick causing overcharging. Also look to the fuse and if the battery is in good condition.

Read the charging guide(s) They explain step by step what and how to check to identify the problem component(s) Check brushes, check connections, measure the resistance of the rotor slip rings, anything below 5 or above 6 is bad. look at the windings of the rotor. if they are very dark and bubbly there's your answer.

 

[TwoManyXS1Bs]

Hey, Spike. Sounds like it's time to go thru the charging system guide(s).

http://www.xs650.com/forum/showthread.php?t=10561
http://www.xs650.com/forum/showthread.php?t=35665

The headlight is a different issue. Part of the life expectancy of incandescent bulbs depends on the power switching cycles. With a poor/intermittant connection (probably from vibration, and faster than you can see), the bulb life can be short. Since power to the bulb is now lost, it sounds like the intermittant connection finally failed. For that, check the schematic for your bike, and trace for power to the headlight...

Edit: Haha, 'ol quickdraw gggGary beat me to the punch...

 

[retiredgentleman]

If your bike still as the old original rectifier and regulator, they are worn out, and likely contributed greatly to your problems. Your charging system is sick and is crying out for some medicine and tlc.

Here's a link to read, to help nurse your electrics back to health. It talks about a nos automotive regulator and modern rectifiers.
http://www.xs650.com/forum/showthread.php?t=21485

 

[Spike]

You guys are awesome.

Thanks for all the info. I really appreciate it. I'll look through all the diag info, do some testing and hopefully have an update this weekend.

 

[pamcopete]

Another possible fault to look for is a miss wired headlight that has both the high beam and low beam filaments on at the same time. This will create excessive heat to the filaments and one of them will burn out prematurely. You may not notice this condition in daylight, but just check once in awhile that the low beam goes out when you select high beam.

 

[XSLeo]

On your headlight there are three wires. The black is ground. A poor ground can and will blow the bulb. I use a H-4 bulb in an after market lense/reflector. It blowed several bulbs before I fixed a weak ground.
The low beam is a green wire. High beam is a yellow wire.
Leo

 

[Spike]

So when I jump the green wire at the regulator connector to ground, it keeps blowing my main fuse. Any ideas on this one?

Should I be disconnecting the connector and then jumping it or just plug my lead in the back of the connector?

 

[XSLeo]

On the 79 you don't do the regulator bypass by jumping the green to ground. You jump from battery positive to the green wire.
On the 70-79 models the stock set up controls the current through the rotor before the rotor. Power goes to reg then if low voltage the reg sends full battery power to rotor, then grounds at the stator housing and black wire to harness ground.
On the 80 up talked about in the guide, power goes to the brush on a brown wire. The green wire goes to reg. When low voltage the reg grounds the green wire.
So on your 79 when you ground the green wire you send voltage straight to ground.
On the 80 it sends voltage through the rotor.
Try jumping from battery positive to the green wire as a reg bypass.
This should show magnetism on the wrench or feeler gauge. If the bike is running it should also show a voltage increase at the battery.
Leo

 

[XSLeo]

Oh, almost forgot. When doing any jumping do it at the brushes. Just touch the jumper to the brush. On yours one brush should have a green wire the other a black wire.
Your stator should look a bit like this one. If you look close you will see the wire colrs and where they hook.
The second pic is what your brushes should look like. One has a short mount strap the other longer and has three holes.
Leo

 

[Spike]

Gotcha! thanks for the info XsLeo.

So here are a couple things so far. I checked voltage with the key on at the green brush terminal and have battery voltage. I also checked for resistance at the rotor brush rings, but not 100% on my findings.

If I touch my leads (one to the outer ring, one to the inner) I get OL (out of limits) on the meter. If I touch both leads to the outer ring I have .3ohms and both leads to the inner I get .4ohms. BTW the rotor is still bolted on, didn't think that should matter. Should I have continuity between the inner and outer rings on the rotor? I know ones + and the other is neg correct? Also just tried taking a good 9v bat and touching it to rotor and I get no magnetism with a feeler gauge.. I'm wondering if I have a bad rotor?

 

[XSLeo]

Yes, you should get some reading from slip ring to slip ring. The winding in the rotor, one end hooks to one slip ring the other end to the other slip ring.
Ah, just a second, a no reading could mean one of the wires from the winding might have come loose. On the side of the rotor look for where the wires from the winding hooks to the slip rings. Check both for a good connection.
A good rotor will read from about 4 to 7 ohms. If lower than 4 there is a short in the wire inside the winding. The 5 ohms is a reading for the I think around 325 of wire in the winding. A short in the winding skips over a portion of the wire. This gives you a lower ohm reading.
It shouldn't matter if the rotor is bolted on the engine or not. One thing about reading low ohms is to test the ohms of just your leads. On your lowest ohm scale, 200 on most digital meters, touch the leads together. the reading you get is the reading for the leads. Now do the test. Lets say your leads reading is .3 ohms, your test reading is 5.6 ohms. Now you subtract the leads reading from the test reading to get the actual reading. As in 5.6 ohms -.3 ohms = 5.3 ohms. You should test this way on all the low ohm readings for the stator and rotor.
The slip rings don't really have a polarity, power flows from the brush to the slip ring, through the rotor, out the slip ring to the brush.
Polarity doesn't really matter, it will still have one negative pole and one positive pole. These poles are the inner and outer end. The plates that make up the poles on each end are bent over around the winding. This forms triangle shaped pieces around the rotor. One triangle is positive the next negative. This is why the out put on the three white wires is AC current.
From reading your results my best guess is your rotor is bad. You might get lucky and get a good used rotor, my best suggestion is to get yours rewound. Call Gary at Custom Rewinds 1-800-798-7282
Leo

 

[Spike]

Alright guys, It's finally above 50 degrees here in Nebraska and I finally got to the bottom of my issue. After testing my rotor finding it was out of spec, I went ahead and bought a used one that tested good. I threw it on this morning and after testing I'm getting a good charge at idle. I rewired the headlamp to factory and put in a low wattage h4 bulb and it is also now working.

I don't know the details on how the headlight circuit works in conjunction with charging system but I know that if you're not getting a good charge, your headlamp probably isn't going to be working.

Also, XSLeo I meant to say thanks for the # to Custom Rewinds. I'm planning on sending in my old rotor to get it refreshed so I have a good spare.

Thanks again for all of the input guys, I appreciate all the tech help. Time to go for a ride!

 

[XSLeo]

Ok On the stator there is a yellow wire, it hooks into the center of the stator windings, it bleeds of some of the power created when the stator creates electricity. As the engine starts the alternator starts to create electricity. As mentioned some is bled off by the yellow wire. This voltage is sent to the safety relay.
As the engine speed increases the voltage on the yellow wire increases. When it reaches about 4.5 volts it trips the safety relay.
When the safety relay trips it shuts off power in the starter relay circuit, stopping the starter from working and keeping it from working as long as the engine is running. On the mid 78 up bikes the safety relay, when it trips sends power to the headlight. On the later bikes they even removed the headlight on/off switch.
So knowing this you that with a no charge situation the headlight on these later bikes won't light.
Leo