SR model voltage regulation blues

jaguar

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Jul 29, 2000
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South America
Well, this is what happened. Maybe you can shed some light on this.
First the low beam burned out, then the other night leaving my friends house I noticed that the high beam was really bright for a few seconds before it also blew. Of course the regulator permitted too much voltage to the lamps but the problem is that this is an SR model of KDX200 and it is different than a normal KDX and the different parts are only available from Japan. But thankfully a fellow forum member in Japan is willing to help me get parts but I'm not sure which. There are 3 parts which could be suspect. Two are on top of the air filter box. One of them is metal and finned and has two wires. The other is a black box with about 5 wires. Also, behind the front number plate is a black box with 6 wires that has 2 relays and some electronics in it. The turn signals still work and so does the instrument indicator lights. So, whachyathink? Any suggestions?
 
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Matt90GT

Member
May 3, 2002
1,517
1
measure the voltage with a multimeter.

If the voltage is spiking above 12-13vs, your regulator has gone south. It is the one with 2 wires on the airbox. you can replace that with an aftermarket regulator like the Moose unit or similar for $15. IF you have a battery, you need a regulator/rectifier. Baja Designs has them for $35.
 
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shr

Uhhh...
Apr 8, 2002
113
0
I would have to think that your tail light is burnt out too.

Also if I'm correct, your bike has a battery too. In that case the battery is part of the system and the battery helps regulate the voltage spikes.

A bad battery can cause an over voltage surge..... Usually the tail light goes first and then the head light.

I don't know that much about the SR's, only that they are a street legal bike in Japan, but if the regulator is the problem you can get what's called a shunt regulator like
Matt90GT said here in the USA
 
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canyncarvr

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Oct 14, 1999
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shr: excellent point on 'battery regulation' capabilities.

How 'bout grounds? I don't know if this SR is used for anything like REAL dirtbiking ;)...but the whole system referenced of course to ground, a bad one of those can give you headaches....although generally more in terms of 'not enough' than 'too much'. Dirtbikes given to mud slime and otherwise things annoying to decent electrical connections.

Along the 'ground' line... having to do with wires in general...if there's an insulation failure-short somewhere between the headlamp 'return' line (it's red on US bikes..feeds the regulator) and frame ground, THAT'll give you a bright light. For a little while.
 
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Boot

Member
Jun 11, 2002
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0
I've got an SR model too. It's never had a battery but does have the other gizmos on the airbox lid and behind the front number plate as jaguar describes. I'd say it'd almost certainly have to be the regulator for this kind of problem to occur.

I'm working on a short in my electrics at the moment and in the course of troubleshooting hooked up a multimeter to the alternator output. That thing kicks out around 20 volts once the engine is spinning a bit. This is plenty to blow a 12-volt filament without a healthy regulator to tame it.

There's also some sort of resistor or something in behind the right radiator. I don't know what it does, but from memory it seems to be more connected with the ignition circuit and not the lighting circuit. Anyone know what it is?
 

jaguar

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Jul 29, 2000
1,507
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South America
rooster

thanks guys. I'll check for wiring shorts to make sure, although I still think it's the regulator. Cool to know there are generic substitutes available. I'll do an internet search.
I'm pretty sure the tail light was still working. When I was checking it I did plug/unplug all relevant connectors to help renew the connections although I did have to scrape clean a couple of them. Yes this bike gets taken through the mud while onlookers scratch their heads and think "them gringos are just plain crazy to muddy up such a nice looking bike".
The black box behind the front number plate is for the turn signals (or so I was told today from the importer I bought the bike from).
No, SR's don't have batteries. They just have more street legal stuff, a smaller carb, and a heavier flywheel which I would love to make lighter. Anyone done that?
thanks again guys
[edit: Moose Volt Pack #M011 $15 from www.mxsouth.com is a 12v voltage regulator for dirt bikes without batteries. yes!)
 
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canyncarvr

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Oct 14, 1999
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'Yeah' on the turn signal box behind the plate. Figured that to be a known issue if you knew what the other two 'black boxes' were.

Keep in mind that the kdx (well...the US model for sure) has an AC regulator, NOT a DC rectifier. Don't know why the SR would be different...'specially if it doesn't have a battery.

Boot:
'Some sort of resistor thing..'
A ballast resistor. Meant to limit current through the coil.

Jaguar:
'lighter flywheel'
Go here:
http://dirtrider.net/forums3/showthread.php?threadid=51834&highlight=flywheel

Contact jc. He turned his down. I have NO idea myself why anyone would want to do this to a kdx...yes, it will certainly rev quicker but I wouldn't want to lose the inertia. To each his own.
 
B

Boot

Member
Jun 11, 2002
98
0
A ballast resistor. Meant to limit current through the coil.

Thanks canyncarvr. This makes sense. Now there's one less mystery to the old KDX.
 

jaguar

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Jul 29, 2000
1,507
82
South America
(I measured mine to be 5.5 ohms.)
Hey Old Member, do you think the Moose volt pack is for AC or DC systems? Its page on mxsouth.com says "12 volt regulator for off-road vehicles without a battery". It only has 2 wires, the same as my stock regulator.
see http://www.mxsouth.com/moose/mooelevolt.htm
 
B

Boot

Member
Jun 11, 2002
98
0
Hey Jaguar, thanks for the 89-94 kips exhaust valve info you've linked to (and posted)? I wish I'd had it a couple of months ago! Great stuff.
 
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canyncarvr

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Oct 14, 1999
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I would suppose the moose thingy is an AC regulator...for use as a replacement unit in your average one-each dirt bike. Note it doesn't say 'rectifier', which should be one of the words used for the 'use on battery' units as matt said.

You lose a LOT of power rectifying an AC signal into a +DC volatge. Hey! Where'd all the -volts go?? ...in the trash. It takes about 1/2 an AC voltage (amplitude) to get you the same power as you'd need in a DC form. Not to insult your BEEP skills (Basic Electronics & Electricity Principles), but 12VAC will rectify to no more than 6VDC, plus or minus. The former will run your lighting system, the latter won't. Not well anyway.

Don't take me to task for period of cycle, latency, watts and such. It's meant to be a simple statement and so has inherent errancies. Hey..did I just make up another word??.....nope...it's in the book!

Yes, I realize output from the bike system (unconditioned) is >12vac
 
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shr

Uhhh...
Apr 8, 2002
113
0
canyncarvr,

You are wrong about the losing 1/2 the voltage when rectifying an AC source.

If a full wave bridge is used there will be no loss! Only if you use one diode in a half wave situation will you lose 1/2 your voltage.

Basic electrical theory.
 
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canyncarvr

~SPONSOR~
Oct 14, 1999
4,005
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cripes!

I said, don't take me to task for crin out loud!

So...where do you use the -12VDC output from a full wave bridge from a 25VAC source in a dirtbike?

I guess you could split it. +12VDC to the headlight and -12VDC to the taillight?

Sheesh. I stand NOT corrected.

I said
.

You lose a LOT of power rectifying an AC signal into a +DC volatge. Hey! Where'd all the -volts go?? ...in the trash.
Click to expand...

Get the 'plus' part?

Basic electrical theory.

Your apology is accepted.

......you can call me rich on this one!
 
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shr

Uhhh...
Apr 8, 2002
113
0
canyncarvr

I don't think you even know what you are talking about.

And NO this is NOT an apology!

You need to do more research about AC voltage and using diodes to get DC voltage from an AC source.

If your AC output is 25 volts and you are sending 12.5 to the head light and 12.5 volts to the tail light. THEN your AC output is center tapped to ground!

AND both the head light and tail light are still running on AC current! NOT one with + voltage and the other - voltage.

If the output is not center tapped to ground then the lights have to be running in series. In this case they would have to be of equal wattage and if one goes out the other one will not light.

The only bikes that I know about that use a series system are old European mop heads.
 

jaguar

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Jul 29, 2000
1,507
82
South America
OK guys, stop bickering. It all depends if a regulator is in series after the full wave bridge. To have a steady DC voltage you'd have to output about half of the peak voltage, otherwise you'd have a ripple voltage DC output. If there wasn't a voltage regulator then the only loss would be the voltage drop across two diodes which would equal 1.2 volts if silicon diodes were used.
Although I am experienced in electronics technology I have never fiddled with a motorcycles electrical system other than changing a battery. This morning I cranked up the KDX and measured about 9 volts AC (when I revved it). I was expecting to read about 15 volts since I was thinking the only logical reason for blowing both my low and high beam filaments in my headlight was the regulator allowing more than 12 volts to them. But none of my other lights are blown (tail and turn signals). Could it be that it was just the halogens time to go?
 
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shr

Uhhh...
Apr 8, 2002
113
0
Sorry jaguar,

I wasn't trying to bicker, just having fun and wanted to express a little knowledge.

I have worked on automotive and motorcycle charging systems for 30 years. I know them very well :) Right down to a 1964 Honda half wave systems

More about voltage, there is peak to peak AC voltage that can't be measured with most volt meters (best read on an oscilloscope) and there's RMS voltage that we mostly refer to. Peak to peak voltage is 1.4 times what most multi-meters read.

So if you read 12 volts on your meter it will be 16.8 peak to peak volts. These spikes are of little value unless you use them to charge a capacitor, capacitors will fully charge to peak to peak voltage. (this is how capacitor motors work. They take your 120 AC house current and charge a large capacitor to 168 volts and dump it into the windings to get a high torque and fast start up. and yes there is 168 volts at your house hold plug)

Now all permanent magnet AC alternators are RPM effected. As the RPM goes up so does the voltage (this has to do with breaking and reversing the magnetic line of flux. The windings in the stator are designed to have a certain wattage out put, so the load can control the voltage out put (load)

Lighting systems without batteries (like yours) use a shunt to ground to dissipate over voltage to ground. This can be a wire wound resistor or a Zener diode (or a combination of both).

This causes any over voltage to go to ground (note they dissipate heat too) Even today's bigger road bikes use this on their permanent magnet alternators.

PLEASE NOTE! checking out put voltage will be higher with NO load (unhooked wires out of the stator) and will also go up with RPM.

Hey guys, don't be mad at me :)

This old dude does know his charging systems, but hey I still say "god bless America"
 

jaguar

~SPONSOR~
Jul 29, 2000
1,507
82
South America
OK, 9x1.4=12.6
so the average (or rms) voltage I was reading is OK? I would of thought that 12 volt rms would be used, and not 12 volt peak.
Have any idea why only the halogen blew? Are they more sensitive? Maybe the connection to the regulator was crappy.
 
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shr

Uhhh...
Apr 8, 2002
113
0
jaguar,

If you were reading 9 volts on your meter, 9 volts is the out put to your system (RMS) and that would be the measurable voltage your bulb is receiving (are you sure the meter is reading correctly? Sounds low if @ above idle RPM, say about 2000 to 3000 RPM's).

It is possible that it was the bulbs time, but with only a 9 volt reading...??? and both elements going out one right after another with a flash bulb effect...???

Have you check voltage at idle and checked it at higher RPM's (are you checking the voltage at the head light it self ?). You should see the voltage go up as the RPM goes up to the point of the regulator limit (at least 13 to 14 volt I'd think)

Note it is possible to have a bad regulator (your 9 volts @ 2000 to 3000 RPM sticks in my mind), and like I said in my last post, the regulator dissipates over voltage (say 13 to maybe even 16 volts).

This creates heat and heat can cause the shunt (regulator) to break down.... and that would cause a problem.

Can you tell me what the wattage your head light bulb is ? The SR system has my curiosity peaked (wish I had a schematic of it), I almost think that they are using a double lighting coil.

Again, I hope my words help, I just want to share my many years of dealing with these problems.

Cheers! :)
 
B

Boot

Member
Jun 11, 2002
98
0
This is turning into a really educational thread.

shr, if I had a manual I'd scan the schematic and post it, but unfortunately I don't. My SR headlight is about 30 watts, both beams. Stock is 25/25 it seems.

9 volts sounds like something is not working. As I said, my alternator seems to kick out up around 20 volts with no load.

By the way, I found that the flywheel had rubbed away the insulation on the brown? lighting wire coming out of the alternator. It had exposed the copper core, and was presumably shorting out periodically or partially. Maybe this would be the cause of your low voltage. Just pull the cover off and you can see how close the wire is to the flywheel and check its insulation jacket.

Also, my headlight unit was very loose when I got the bike. It just sort of sat in place vaguely located by a couple of plastic lugs. It vibrated like crazy and I just knew it would kill the bulb like that. I shoved some silicone around it to hold it more tightly and absorb some of the vibes. Doubt this would be your problem, but worth a mention.
 
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canyncarvr

~SPONSOR~
Oct 14, 1999
4,005
0
shr:
You're right. I don't know what I'm talking about.


I've only been repairing electronic gear and digital equipment for the past 28 years, not nearly as long as in your case, evidently. I have NO idea what 'root-mean-square' means, I think o-h-m is some sort of religious mantra and isn't di-ode some old guy that has assumed room temperature?

Pick all you want. It's good for a laugh:)

Ha! The last guy (with over 30 years experience, btw) that worked on a wiring problem in my wife's car replaced a fuseable link with a hunk-o-wire..... 3 years later the car ended up as a totaled vehicle due to the fire (well, and the water dumped into the car courtesy of the fire department) caused by that cute little bit of decades of experience.

That's ok. I rewired the whole thing. Worked from stem to stern first key twist. Painted it. Worked better than ever (a lot of work just to get to that pesky O2 sensor!)!


I amaze myself with my stupidity! I am an absolute moron!!

Please accept my absolute, abject and most humble apologies.

Cheers
 
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shr

Uhhh...
Apr 8, 2002
113
0
Oh canyn,

You da man, you daaa man! I will not write anymore as you da man.

Hail to the great canyncarvr, as he is da man! Long live the carvr!

You should be the moderator of this site as you KNOW ALL!

I will now believe that KDX's have 25 volt system and the head light runs on the + voltage and the tail light runs on the - voltage.

Who says you can't teach an old dog new tricks....., I'm a believer now, cuz you da man!

thank you canyncarvr for setting me straight and teaching me how a real KDX lighting system works.

You da man :)
 

jaguar

~SPONSOR~
Jul 29, 2000
1,507
82
South America
shr, please don't leave. Sometimes people react negatively to innocent statements because that's their pattern. Usually mental patterns are established when young and take some concentrated effort to break when older. Take me for example. I was put down and criticized a lot when young and as a result I have a pattern of thinking that people are at least "thinking" negatively about me. But now I just try to be above it all and spread some love around and always give people the benefit of the doubt. Even if they are trying to be negative, I come out the winner because I maintain a good feeling within despite what's going on without. Well, not all the time. I'm still trying to perfect it.
Anyway, back to the topic.
Yeah I thought the output voltage was low. I remember now that I replaced the horn before and it still didn't work.
Maybe the regulator is getting really funky and sometimes letting too high voltage out although normally keeping it too low. I'll replace it with the $15 Moose "volt pack". What hurts is looking at the $45 price tag on the kawasaki replacement bulb. continued...
 

jaguar

~SPONSOR~
Jul 29, 2000
1,507
82
South America
I saw on one site that a 55/60W halogen was used to replace the 30/30W that's on it now. I just hope that if I go that route that it won't burn anything out. Being down here in no-parts land can really be a bummer sometimes. That higher wattage bulb is an H4 style (that I'd have to either find a connector for it or solder wires directly to it) for $8 from JCWhitney.com
Last thought I'd like to throw in about people bickering. I also used to be highly competitive mentally and I think that racing influenced that. After I noted how most of the racers were very ego-centric, prideful, and ready to bump anyone off the track I decided I didn't want to go that route. I don't care if I have a trophy. I left my 3rd place trophy behind many years ago. I just want to have a good time. I think more people ought to lossen up and just go trail riding with their buddies. I'm not competing in life with others any more, just doing my own thing and trying to enjoy myself and help others to do the same. OK, 'nough said.
 
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shr

Uhhh...
Apr 8, 2002
113
0
jaguar,

I enjoyed your words of wisdom, we all could be better people if we practiced it. Thank you for your thoughts :)

As for your bulb, using a higher wattage one can put more load on the stator and the wiring running it. Also the bulb would not be as bright.

I looked at that bulb chart link and I also had a problem reading the dimensions....???? I did however see a 12 volt one that was a 45/40 watt (G40P45T-124540). But I don't know if you can mount it where it needs to go (this is a little closer to your stock wattage).

Yea the Jap's really have us over a barrel on just about every small bike with a head light. Some come as a sealed up unit (the bulb is part of the lens and reflector. In the past I have cut them open and mounted a suitable inexpensive automotive bulb.

I wish you luck and think you will come up with a good alterative. Just remember that to much wattage (load) can cook other things.

Again I enjoyed your comments :)
 
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