83 KE125 - Electrical problem

[JulianKo]

I restored a 1983 KE125 Enduro, but I am having a hard time with the electrical system.

I had ridden it without a battery and without any lights attached a few times and tested the horn and it worked fine.

Then one day I added blinkers and a 12V bulb ( I did not have a 6V bulb at the time) at the back, started the bike and while I noticed that the light from the bulb was too bright, it burned all bulbs. The engine continued to run, but it looks like the voltage (or should I say the wattage) became so weak, the horn barely makes any sound anymore and any 6V bulb I put, barely glows.

The situation deterioted further, when I rode it last time. I made a few miles perfectly fine and then the engine started sputtering at mid to higher RPMs, I barely made it back.

Thinking that all this was because I did not have a battery, I bought a brand new one.

What I notice after connecting the battery is this:
- The lights come on as soon as I connect the battery and I can't turn them off from the key, no matter in which position it is turned into. The only way to turn them off is by disconnecting the battery. Not sure if this is a contact switch problem or wrong wiring...

- The brightness of the lights is not affected by how much throttle i give, which tells me they run off the battery and it does not get charged.

Can someone who knows this stuff tell me:
- Is my rectifier/regulator burned? I looked at it - there are no visible sighns of damage, but it gets hot to the touch a minute after I start the bike.

- Could it be that my generator broke all of a sudden. I tried to measure the voltage without the battery between the (+) connector for the battery and the frame and the voltmeter got nuts showing all kinds of voltages between 3 and 13V changing fast.

[RCW]

I would vote that it is time to have the regulator/rectifier checked. I suspect you shorted the rectifier that handles the output feed to the battery. They include a type of Shottky barrier diode and have a voltage limit at which they will break down and fail.

What happens is the Shottky acts as a one way switch and once it burns out it will feed through and look for a ground. The lighting circuit provides enough ground that what power leaks through will make them glow dimly.

But, before you do that check the fuses and make sure you did not blow the main generator power output fuse. If memory serves me correctly these had three fuses in a rubber holder down under the side cover. Also, check your tail/stop light and make sure the bulb has not burned one of the filaments and dropped it on the post to the other. That will also make the lights glow dimly any time it is started.

If the fuses, tail light bulb, or the rectifier are not the problem, then you need to pop the flywheel and test the top two charging coils for continuity and/or a short.

Back in the day these were stone simple. They use breaker points and a magneto pulse and then ignition coil is kept up to the required 6 volts by the battery. Sort of a hybrid magneto that always had enough voltage to make it easy to start.

If you take a look at the parts diagrams you will see three generator type coils inside the flywheel. Two are for the lighting system and battery, and one is the exciter for the magneto.

I also suspect your battery is below charge specifications and needs to be charged to avoid sulphation and being ruined.

It is not a good idea to use 12 volt lights on a 6 volt system. The regulator is demand driven and will cause the generator coils to pump their hearts out trying to keep up with the voltage. So, ask for more than it was designed to produce, and something will break.

[JulianKo]

RCW, thank you for your expert reply.
As someone, who knows nothing about electrical circuts, I will ask for some additional clarifications:

1. Do you think that the fact that I cannot turn off the lights from the ignition key shows a blown rectifier, or this is a separate problem of the switch itself of wrong wiring (I had taken the whole wiring off, as I painted the frame)?

2. Do you think the engine sputtering is due to a blown rectifier?

3. Is there any way I can test the blown rectifier theory. For example I unplugged all wires from the rectifier (3 single and one harness) while the engine was running one at a time and nothing happened. Should I unplug all at the same time? Can this cause more damage?

4. I found 2 fuses in a rubber holder under the seat and both look good.

5. The tail light is a brand new 6V and is good - both filaments work.

7. I have put LED turn indicator bulbs on the handlebar panel and they worked fine before. Now the both barely glow (or twinkle) at all times (regardless of the turn signal switch position)

8. Is it possible to check the generator charging coils without poping the flywheel. Which side of the engine is the flywheel? If it is on the left side (by the gear shifter) I have two philips screws, which I cannot remove as the heads are busted... But there is a wire harness that comes from under the sprocket cover and maybe I could measure for continuity there?

[JulianKo]

I think I have narrowed the problem.

I opened the left engine cover and I sprayed the coils and the contacts with Electrical Cleaner. The byke started right up, had tremendous power, no hesitation and all lights worked nice and bright.

I rode it for 15 min, then went to change and tried to ride it again. The second time it was worse and eventually it died (no spark). I had to wait 15 min, and when it cooled off a bit it started, ran for half a kilometer and died again.

I repeated this several times - it would start when it was cold, but then died when it got warm. The problem is under the flywheel. My question is can you tell me if it one of the coils (and which one) or could it be the contacts. What happened when I sprayed them with Electrical Cleaner? Everything seemed clean there to begin with. The only strange thing I could see was something that looks like clear droplets of epoxy or lacquer on the copper coils, but other than that - no signes of melting or loose contacts.....
I was wondering if this was not a sign that the coils have been overheated and if they were is it possible that some of the insulation has leaked out and they short when they get hot... Or maybe the condensor can cause that...What is its role anyway?