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Old 12-20-2007, 01:59 PM   #1
Windfield OP
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Question LC4 voltage problems

Hello all, I'm new here but have been riding my 1995 620 LC4 for around 6k, I recently came back to it after a 9 months abroad, both high and low beams are burnt, both blinkers went on my first ride, I would guess the voltage regulator is toast but any info or knowledge on this would be helpful.

thanks

Windfield
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Old 12-20-2007, 02:52 PM   #2
Luke
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That sure sounds like a bad regulator. If you can, measure the voltage at the regulator output or battery or headlight. If it's more than 14.5V, you need a new regulator. The bad news is the battery is probably dead too.
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Old 12-20-2007, 05:27 PM   #3
Windfield OP
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Bluhduh voltage test??

I ran the bike and tested the voltage, it read somewhere around 20v without a load (as both lights are gone and I live far away) So it sounds like I need a new regulator, does any one know if you can order one on-line? My bikes a
95 lc4 the generator puts out 130w so could I use a different one? again, thanks for your time and anything helps,

cheers, Windfield
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Old 12-20-2007, 07:51 PM   #4
Luke
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20V? Yeah, it's toast.

I'm not very familiar with the SEM ignition. Do you have a wiring diagram by any chance? Do the wires coming out of the stator match the colors on this page: http://www.transmic.net/sem.htm ? If so, a cheap two-phase regulator from BajaDesigns.com or TrailTech.net should do the job.
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Old 12-20-2007, 09:58 PM   #5
Windfield OP
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thanks

Luke, thanks a lot there, I'll order in some part and see if it's fixed, If not I'll be back here asking around again. Cheers, Wind
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Old 06-17-2008, 08:29 PM   #6
DIRTYNIDGE
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Hopefully I can jump on this thread as it seems similar to my problem, maybe....

I have recently purchased a 93' LC4 EGS400 and was reassured by the seller on purchase all electrics work, just rec/reg had been taken off as lights not required. Just to clarify, this model has no battery only capacitor.

I pulled the covers off after purchasing the bike and found a rec/reg was fitted but checking on the capactior with my trusty fluke there was no voltage with the engine running at idle, I fitted a spare rec/reg which came with the bike (still in KTM box) and found the same.

I then unplugged the connector to the stator, tested and discovered 30V open circuit voltage, which I believe to be ok.

My guess is there is still a rec/reg problem, but I am hesitant to fit a new one until im sure there is no underlying problem which is causing them to fry, even if the capacitor is stuffed I would still get voltage out of the rec/reg if it we working wouldn't I? As there is a spare rec/reg and capacitor with the bike I am guessing the previous owner has tried them and failed, Im not keen to make the same mistakes!! Any other check I can do before plugging in yet another rec/reg??

Any thoughts greatly appreciated
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Old 06-18-2008, 12:25 AM   #7
Luke
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Quote:
Originally Posted by DIRTYNIDGE
Hopefully I can jump on this thread as it seems similar to my problem, maybe....

I have recently purchased a 93' LC4 EGS400 and was reassured by the seller on purchase all electrics work, just rec/reg had been taken off as lights not required. Just to clarify, this model has no battery only capacitor.

I pulled the covers off after purchasing the bike and found a rec/reg was fitted but checking on the capactior with my trusty fluke there was no voltage with the engine running at idle, I fitted a spare rec/reg which came with the bike (still in KTM box) and found the same.

I then unplugged the connector to the stator, tested and discovered 30V open circuit voltage, which I believe to be ok.

My guess is there is still a rec/reg problem, but I am hesitant to fit a new one until im sure there is no underlying problem which is causing them to fry, even if the capacitor is stuffed I would still get voltage out of the rec/reg if it we working wouldn't I? As there is a spare rec/reg and capacitor with the bike I am guessing the previous owner has tried them and failed, Im not keen to make the same mistakes!! Any other check I can do before plugging in yet another rec/reg??

Any thoughts greatly appreciated

30V sounds good. Check the resistance of the same wires with the bike off. It should be one ohm or so.

Do you have a wiring diagram? Your bike has an SEM stator and ignition, right? Black Red Green Yellow Blue wires coming out of the stator on separate bullet connectors?
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Old 06-19-2008, 06:29 PM   #8
DIRTYNIDGE
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Quote:
Originally Posted by Luke
30V sounds good. Check the resistance of the same wires with the bike off. It should be one ohm or so.

Do you have a wiring diagram? Your bike has an SEM stator and ignition, right? Black Red Green Yellow Blue wires coming out of the stator on separate bullet connectors?
I will check wire colours tonight but I checked the generator voltage on a 2 pin plug which plugs into rec/reg. The capacitor is definately in the right way round but may be shot, I would still expect to see the power out of the rec/reg on the capacitor terminals even if it was knackered wouldnt I?
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Old 06-19-2008, 06:41 PM   #9
Frank Warner
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Check the capacitor useing your resistance meter .. should start around 0 ohms and rise up to some value .. say 500 ohms ... if it stays at say less than 5 ohms it is toast. If it does not start near 0 homs it is toast... note that to restart the test you should short the capacitor leads together to get rid of any stored charge.

Check the stator is connected through to the rec/reg... it won't work it it is dissconnected.
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Old 02-09-2010, 10:44 PM   #10
olekils
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More Voltage Problems

Hi,
I have had similar problems with my '95 EXC. I recently got it and replaced the headlight bulbs which promptly blew out the first time I reved the engine. Measured Voltage at the output of the regulator (491 11 434 000) and it showed 15-17 V at idle, quickly jumping to 40V at higher RPM. I tried to order a replacement and was told it has been superceded by part# 58311034200 which I installed. I only get about 0.4 Volts on the output side, just enough for a dim glow on the small headlight bulb. The voltage seems steady at higher rpms as well, but seems to jump a small amount when the engine cackles at low rpm. I don't have a battery installed on the bike.
Any thoughts?
Thanks!
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Old 02-09-2010, 11:02 PM   #11
wrk2surf
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pulser coil?
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Old 02-09-2010, 11:11 PM   #12
olekils
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ummmmm....what's that?

The bike runs fine, and when I put the old reg back on, it's back to 17V at idle/
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Old 02-10-2010, 12:33 PM   #13
Luke
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Quote:
Originally Posted by olekils
Hi,
I have had similar problems with my '95 EXC. I recently got it and replaced the headlight bulbs which promptly blew out the first time I reved the engine. Measured Voltage at the output of the regulator (491 11 434 000) and it showed 15-17 V at idle, quickly jumping to 40V at higher RPM. I tried to order a replacement and was told it has been superceded by part# 58311034200 which I installed. I only get about 0.4 Volts on the output side, just enough for a dim glow on the small headlight bulb. The voltage seems steady at higher rpms as well, but seems to jump a small amount when the engine cackles at low rpm. I don't have a battery installed on the bike.
Any thoughts?
Thanks!

The capacitor is only rated for 25V. 40V likely blew it up. Test it; either by following the procedure in the service manual or the way Frank Warner described a couple of posts ago.
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Old 02-10-2010, 03:46 PM   #14
olekils
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Thanks,
I'll check it tonight!
Since it is after the regulator, should the output of the regulator not be 12 V when disconnected from the capacitor?
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Old 06-15-2012, 11:50 AM   #15
misterlink
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Same problem - blown out headlight, regulator or stator bad?

I have a similar problem - I just got a 1995 KTM LC4 400 (I think it's the Super Competition model, see pic below - I can supply the VIN if that helps). It had been sitting for 8 years and I got it for a good price - after cleaning the carb and fixing some other odds and ends, I fired it up and the headlight worked until I revved the bike and it quickly blew out.





I checked the voltage going to the headlight, and the readings were pretty weird (all readings are in AC volts):



Switch set to "high" beam
8V to the Green (low beam) lead (I assume there shouldn't be any voltage here)
12.5V (idle) to 20V (revved up) to the Blue (high beam) lead

Switch set to "low" beam
12V (idle) to 12.5V (revved up) to the Green (low beam) lead
16V (idle) to 20V (revved up) to the Blue (high beam) lead (I assume there shouldn't be any voltage here)

Obviously, the 20V is what blew the bulb, although judging by the readings you'd think only the high beam filament would have gone. Both filaments blew (if I remember right, they blew at different times within the few minutes that I was testing the headlight so both the high and low beams must have gotten big spikes in voltage).

Does anyone have an idea why there was still voltage going to the high/low headlight leads even when the switch wasn't selected on that setting? The interesting thing is that my test light with an LED bulb only lights up as expected, when connected to the high lead and the switch is set to high and when connected to the low lead and the switch is set to low (it doesn't light up when connected to the low lead and the switch is set to high, and vice versa).

I also checked the voltage readings to the tail light, and at first I got some high readings but then they stayed more normal. Here are the readings I'm getting now (also in AC volts):

Running light ("low" filament in tail light switched on)
4V (idle) to 2V (revved up) to the high beam lead (I assume there shouldn't be any voltage here)
11.7V (consistent at idle and revved up) to the low beam lead

Brake actuated ("high" + "low" filaments in tail light switched on)
12V (idle) to 13V (revved up) to the high beam lead
11.7V (consistent at idle and revved up) to the low beam lead

The tail light is working fine now; the high readings I saw initially around 16-18V stopped after I connected the brake light switches to the master cylinders (they weren't hooked up originally) - maybe that fixed the problem.

According to the wiring diagram, it looks like the two voltage regulators only connect to the brake light and not the headlight. Take a look at the diagram below - do you guys think the headlight is just getting straight unregulated AC power from the stator? That's what it looks like to me.



A mechanic I talked to thought that if I was getting AC (not DC) voltage to the headlight, it probably means that it's coming straight from the stator and not going through a regulator first (since most bikes run the majority of the system on DC). If that's the case, then it doesn't make sense that the tail light voltage is also AC. Does this entire bike just run on AC? I guess since it doesn't have turn signals or much to run other than the headlight, tail light, and tachometer light that could make sense.

Anyway, I just need to figure out if I need to replace one (or both) of the regulators, or if I need to replace the stator. I've spent many hours reading all of the helpful stator threads here, here, here, and here. I compared my stator readings to those in these threads, and the resistance readings look more or less normal although the voltage readings seem to be off:

Stator Output Voltage (varies a ton when kick starting the bike)
Black to Red: 6-33V AC (on Luke's post here he says it should be 100-200V AC)
Black to Green: 1-20V AC (on that same post Luke says it should be about 1V AC)

Stator Resistance
Black to Red: 1636 Ohms
Black to Green: 23.5 Ohms
Red to Green: 1659 Ohms
Yellow to Blue: 0.1 Ohms (on other threads it looks like this should usually be 0.2 or higher)

Coil Resistance (checked it just for the heck of it to make sure the stator hasn't damaged the coil - even though the bike still runs)
Orange to Red: All over the place - 0, 0.5, 1.5, 0L
Blue to Green: 99.7 Ohms
Spark plug wire to Black: 7020 Ohms
Spark plug wire to Green: 7110 Ohms
Spark plug wire to Orange: 54000 Ohms
Spark plug wire to Red: 54000 Ohms

I'm pretty sure the wiring diagram shown above is the right one for my bike (the owner's manual I have covers a bunch of different models and has a bunch of wiring diagrams). Does anyone know where I can get a more detailed shop service manual? Here is a pic of the owner's manual cover:



All of the components on the wiring diagram match up with what I'm seeing on the bike except that I don't have a horn. Also, I noticed a couple of loose wire connections behind the headlight - it looks like this one goes to the tachometer light (which isn't in use now because an aftermarket ICO trip meter has been installed):









And according to the wiring diagram these wires should probably go to the "high beam control" (#2 on the diagram). I'm not sure what that is - any ideas? This is separate from the combination switch for the headlight, horn, and kill switch (#4 on the diagram).



On this bike, according to http://transmic.net/en/sem.htm it looks like the CDI is built in with the coil, right? I want to make sure I don't damage the CDI/coil by riding it too much while the voltage is so high. I assume it's best to not run the engine any more than necessary until I figure this out, right?

I rode the bike around yesterday and it started sputtering a little on me; it kind of felt like it was running out of gas or fouling the spark plug. It cleared out though and ran pretty strong for a while too. It could very well be a carburetor issue (the bike started with 1 kick and ran perfect at first after I cleaned the carb, but is now hard to start and leaks gas out of the carb overflow after I'm done riding) but I'm wondering if it could be also be an electrical issue. I'm waiting for the carb gasket kit (on backorder, probably coming from Austria) and I'm hoping that once I put in all new gaskets and o-rings in the carb it will fix the sputtering and leaking issue (I already installed a brand new needle & seat valve).

Anyway, I'm pulling my hair out on this one - kind of stuck and I don't want to buy the wrong parts. If anyone can help point me in the right direction as to whether I should get a new stator or voltage regulator(s), that would be awesome!

Lincoln
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