Combo Regulator Rectifier - 79 XS400F

It's not a myth that the stock regulator is wired to the field coil and that those diagrams don't show that happening.

Yes, there are other ways to do it, but to suggest a wiring diagram that is totally different from stock as the correct way of doing it without mentioning the differences, whether better or worse, is any easy way to confuse people that might not be as familiar with the bike and the wiring.
A newbie could look at those diagrams, wire in a matching regulator/rectifier, totally leave the field coil out, and have a completely non-charging bike. They'd have enough juice in the battery to start, drive out of town, and get stranded on a back road somewhere.

For people more comfortable with electronics, yeah, the field coil could be rewired to run straight off the battery voltage, maybe wire the stock regulator to run off the kill switch with the ignition coils, or maybe someone that doesn't like kickstarting could throw a latching relay in that engages the field coil with the starter button.
 
Yes sir you are correct.
To suggest an alternate for the plebian (literal not derogatory) is perhaps irresponsible.
My post was intended for the more advanced.
I'm doing a rewire using an entirely different set of rules and when I get the chance I'll probably change the system to a PMA type but as I see it, the system works and at this point I'm just working on doing a custom bike as neatly as I can. Not re-invent the wheel.
My point was, that there are alternates that can use a variety of switching,
I am using a tech philosophy that has its roots in radio control brushless, (Drones, Planes and Cars) which all use a 3 phase application (some are even sensored to supply a regulation to the coils). All of which use high current AC switched through very high speed circuits with incredible reliability.

My point is that a standard 5 wire reg/rec will work but you must supply a field coil feed from a stable source then the system will work. Another minor circuit, switched from the master, to give the field coil some power to generate a magnetic field.
I'm going to use a simple off the shelf regulator circuit to give the coil about 13.5v when I'm powered up so we get some grunt to make a charge.
 
My shake down on the new electrics will effect my final arrangement but I am assuming that the field coil draws less than 3 amps and if so, a simple and cheap hard wired regulator circuit, independent of the charging, (straight from the battery) will give a simple, reliable charge from the alternator.
I might add at this point that I'll be using LiFePo4 batteries not Li-on. (Lithium Ferrite Phosphate). So I'll use 4 cells in series with a closer match to the standard of the system.
 
Decided to reinvigorate this slightly old thread, I have a combo reg/reg, with everything seemingly plugged in as it should there's no power to the field coil through the reg/red as such, which made me think either the field coil was falty or the stator was faulty, but knowing nothing about these non constant magnet systems bought another set even tho all the meter tests on the reg/rec stator and field coil seemed fine, so I also rigged the field coil directly to the battery and we had a magnet, put the stator cover back on, fired the bike up and the stator pumped out some nice AC Voltage.
But I still know virtually nothing about electrics..
So had a fiddle today and plugged the reg/rec in and unplugged the field coil, put the positive from the meter into the brown going to the field coil, and the negative to the frame, and got voltage, yet when I plug the field coil in the field coil doesn't magetise...
 
The brown should always read battery voltage.
The green wire is the important one.
Depending on the operation of the regulator it will either output a variable positive voltage depending on battery charge levels OR it will vary how much power it allows to pass from the field coil to ground.

In the first case the other, non-green, wire on the field coil should connect to ground.
In the second case the other wire on the field coil would connect to the brown wire in the harness, positive battery voltage.

See what the green wire does with the bike running, then see whether the other field coil wire goes to ground or +12V.
 
Here's a picture of what I have, maybe some sense can be made of this.
 

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Surprisingly useful. Looks like the connector that your red meter lead is on has green, sky-blue, brown-red, and brown wires?
That means your field coil has one terminal on + battery voltage from the brown wire and the other end on the green wire.
That means your bike would have originally had an electronic voltage regulator.

It needs a voltage regulator where the green wire is a path to ground, controlled by the voltage regulator.
Test your regulator's green wire when the bike is running, preferably with the battery slightly run down, not fully charged. If it reads a positive voltage from green to ground, it will not work with your field coil as it is currently wired.
 
Would have had to be a 250C or SE with that connector configuration.
Everything depends on the function of your aftermarket regulator. If the green wire puts out a positive voltage you may have some minor rewiring to do.

If it doesn't put out a positive voltage it's likey controlling the field coil's path to ground, like the stock regulator.
In which case it should work, but isn't.

Need to figure out what that green wire is doing.
 
The only thing I know for sure is the other two wires are for the oil and neutral sensors, which both work.
When I did the same with the green wire there was no voltage reading, but I havent been back to the bike yet.
I'm thinking plug the brown wires in and put the meter between the green connections and see what happens,
not sure why I haven't done that yet....
The green wire from the field coil seems to do a fat lot of nothing, no voltage or anything.
The original had a ground wire, the combo has a ground wire, but if the regulator part or the reg/rec isn't grounded by the ground wire, I/E a completely seperate unit then the regulator side isn't grounded..
 
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but then they cant be seperate ...
 

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Testing green to green isn't testing for anything, except maybe curren. You're more likely to get false results.
The most important thing here is to determine what the regulator does with its green wire.
Have you found a wiring diagram for your regulator yet?

As for the field coil:
I'm pretty sure in one of your posts you mentioned the ohm reading?
Have you tested the field coil's resistance?

With the field coil brown wire connected, the field coil green wire disconnected, and the bike running, you should read 12V from the field coil green wire to ground.
If not you may have found your problem.

From your test result I would guess the regulator must be controlling the field coil's path to ground. What is the reading? 60 ohms?
Could be totally irrelevant since it's an electronic rather than resistive-mechanical regulator.
 
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I think the field coil is fine, when I wired it up difectly to the battery and started the bike I got ac voltage from the stator.
There's no voltage from the green wire to ground, but there is from brown to ground.
As for the reg/rec wiring diagram, no clue as it came with the bike when I got it..
 
Ah.
Which wire/wires did you hotwire to the battery?
Brown to + and green to -?

Kind of hard to tell what's going on. Could just be a wiring issue, an incompatibility between current harness wiring and regulator, or the reg could be junk.

Seems like it should be working.
 
Yeah br + Gr -
I've ordered another Voltage Regulator, I'm hoping it'll run with the 2 seperate units (seeing as the only connection between the two sides of the reg/rec seems to be
the ground wire) until I can figure out whats wrong.

I'm also thinking about reversing the green and brown wires and see what happens..

It does seem like it should be working tho..
 
Yeah, the rectifier half should work just fine on its own.
Which new regulator did you order? Stock for your model year?
 
Thats coool, hopefully :)
I found it on ebay from some breakers, says it's from a 400, but everyone says the 400 and 250 are almost exactly the same, and it's not the mechanical one so hopefully everything shouyld be okay, guess I'll find out next week...
 

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