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Discussion Starter · #1 ·
Hey everyone

I have a '99 XR250 and I've decided to set it up to be road registered. The problem is the old lighting circuit has been hacked up by the previous owner. There's not much of the original wiring left so I had to start from scratch.

I basically just simplified everything to run individual circuits eg. left blinkers, right blinkers, park light circuit, head light, high beam, horn, brake light.

I found the 12v power wire from the voltage regulator under the seat and used this as a common power for each circuit.

The problem is, I started it up and it fried the voltage regulator which now doesn't supply anymore than millivolts.

I had another look and realised there is actually 2 power wires on the bike. The one which now no longer works - but did supply 12v D/C, and another which seems to be supplying 4v A/C.

So my question is, what is the purpose of 4v A/C? At first I thought the 4v circuit may be for the parking lights... but it's A/C?

Also, have I overloaded the voltage regulator by running that single wire as a common power wire? and if so, what is the solution to get power to all the circuits without overloading it?

Thanks in advance for any help
 

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Discussion Starter · #2 ·
Ok, another question... The voltage regulator I just removed has 2 wires... 1 for A/C in and 1 for D/C out.

I'm looking for a replacement and most of the XR regs have 4 wires.

Is it possible that it's supposed to have a 4 wire reg?

Do the 4 wire regs have 2 circuits - 1 to maintain a 12v output and 1 to maintain a 4v output?

Thanks again
 

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Snotty lane fan!
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Hi Knuckles.

I've got a manual for a '96 and that has a 4 wire reg only, PINK & YELLO in GREEN & WHITE/YELLO out.

Stretchy.
 

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Discussion Starter · #4 ·
Thanks for the reply. The one on this bike only has a green wire and a yellow wire.

Looks like I'm just going to have to sit down and test every circuit individually until I find the problem. If there isn't one then theoretically it will have been caused by a faulty voltage reg. Like one of the techs I used to work with always said "Everything is easy, it's all just a process of elimination."
 

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Red Blooded Biker
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Ok, another question... The voltage regulator I just removed has 2 wires... 1 for A/C in and 1 for D/C out.

I'm looking for a replacement and most of the XR regs have 4 wires.

Is it possible that it's supposed to have a 4 wire reg?

Do the 4 wire regs have 2 circuits - 1 to maintain a 12v output and 1 to maintain a 4v output?

Thanks again
A voltage regulator will only keep a voltage tapped at a predetermined level eg. 12v...be it AC or DC. But you would need a rectifier to change AC to DC.

OK, I'm a Techi myself (RF) and still find automotive electrics a pain in the A*se as it's so crap!

OK study the lower of the 2 circuits in this post;

http://www.xrv.org.uk/forums/xr/32532-where-tap-into-leccy-circuit-power.html

You can see the 2 wire reg in there.

Let us know how you get on.

Stretchy.
On the circuit diagram shown for the XR400 the regulator is for a 12 volt AC system. On my XR400 with the standard 80 watts 12v AC output, there is just enough to power the head & tail-light, but insufficient for an AC horn & a brake light...the system would be overloaded.

I bought an uprated 200 watt alternator winding kit from these people
Electrical parts for motorcycles - regulator rectifiers generators stator kits ignition & lighting coils ht & pulse coils cdi units starter motors rotors & have wired it to use the standard windings for the low wattage requiring items & the higher wattage output windings for the heavier items like the AC horn.

Now, as far as what the standard wiring is on a '99 XR250, there may well be a lot differant between what the 400 is & what the 250 is, so I would start by identifying which items are fed by the AC output of the 250. A two wire device may well be a voltage regulator, where anything over the predetermined voltage ie. 12 volts in bled off to earth or chassis. This is called the 'avalanche' effect.

Zener diode - Wikipedia, the free encyclopedia

This is typical for a simple type of voltage regulator. The following is some reading on rectifiers.

automotive rectifer - Google Search

All electrics & electronics are pretty simple...it's all about current flow, be it conventional or electron flow. I used to be a radio & radar engineer in the Navy & nothing has changed that much on cars or bikes for years.
 

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Discussion Starter · #7 ·
On the circuit diagram shown for the XR400 the regulator is for a 12 volt AC system. On my XR400 with the standard 80 watts 12v AC output, there is just enough to power the head & tail-light, but insufficient for an AC horn & a brake light...the system would be overloaded.
The model I have has a standard headlight, tail/brake light, horn (and I was told it had indicators fitted previously before I bought it).
So theoretically, the standard system should not be overloaded by fitting these components again yes?

Now if the voltage regulator I fried, is a voltage regulator... then is there also a rectifier fitted somewhere?

I was told by one person that there is a REGULATOR under the seat (check) and a RECTIFIER behind the headlight (umm... nope). On ebay the item I need to replace is listed as a REGULATOR/RECTIFIER????

I called a wrecker to source the part and he didnt know what I was talking about (no surprises).

I've looked at the wiring diagrams and none that I have found online seem to be like my bike unless someone has removed parts off it earlier in life. I haven't worked on cars or bikes in about 8 years and I am more than a little rusty... especially with electrical!

What I'm thinking: the item I have fried is actually the RECTIFIER as it puts out DC. The REGULATOR must be located earlier in the circuit and supply the RECTIFIER with 12v AC and also have another output of 4v AC.

This then means that it may have originally been fitted with a 4 wire RECTIFIER with an input and output for each circuit (4v and 12v respectively).

And in conclusion I should buy a 4 wire RECTIFIER (which is being listed on ebay as a REGULATOR) and supply it with 12v AC and 4v AC supply wires... or am I way off?

:confused::confused::confused::confused::confused::confused::confused:
 

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This may not be that helpful but here goes.

Old XR250s (early 1980s) have 2 wire regulators (dark green wire and yellow/white stripe wire). They will regulate the alternator voltage to a steady AC voltage.

1986 to 1991 XR250s have a 4 wire regulator (Dark green, yellow/white, pink and yellow) but again the bikes electrics are AC

From then on (I think) there were two models: one with the bare minimum of electrics and one with a full set (XR250R and XR250L?). The one with full electrics had a battery, fuse box and 6 wire combined regulator/rectifier and hence DC electrics, the other still had the 4 wire regulator and AC electrics.

So firstly it sounds like your 2 wire regulator was from an older bike. Secondly, a 4 wire unit is probably still a regulator (2 wires from the alternator in and two wires 12V AC out. And lastly, if it did have indicators, horn etc. fitted originally, then wouldn't it have been a full DC bike and also had a battery and fuse box?
 

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Discussion Starter · #9 ·
Thanks Splasher... that is useful info.

The bike was road registered by a previous owner which means it did have indicators BUT they may well have been aftermarket indicators like I'm fitting now. I'm fairly certain my bike is an XR250R which would have had the basic electrics.

As long as I can find a way to wire Headlights, Park Lights, Brake light, indicators and horn without burning out another regulator then I'm sweet...

This was my original task but something that seemed so simple has gone terribly wrong... either at the fault of the regulator, the cheapo switch assembly from china, or my wiring (which I have checked and rechecked and can't seem to fault).

As frustrating as it is I think I might just remove everything off the bike, buy a new reg (4 wire I guess?) and start all over again step by step.

Thanks to everyone for all your help.
I would say I'll post the fault when I find it but since I'm starting again it probably won't be found... ah well here goes...:cussing:
 
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