Calling on Yamaha Rectifier Regulator experts

[old_skool]

Hi all, been awhile since I've been here, I've been on the GSR for quite some time now with a hefty collection of GS-es, but recently acquired another XS1100, an 81H and will be doing some work on it in the near future, will be looking for any standard titled frame, as this one was lost and P.O passed away...and Ohio is a title Nazi state. Anyway, a quick question or two.

I'm pretty familiar with most RR's but the Yamaha's, I have an extra XS1100 RR and was wanting an explanation for the extra wires. It has what most RR's have, 3 stator and a hot and ground, now for the other 2, tan and dark green, the wiring diagram shows the tan going to the fuse box, same as the hot, is this a sense wire? And what is the purpose of the DkG wire, I'm assuming something to do with the fact these Yamaha's have a field coil separate from the stator.
The real question is, can I use this RR on a non-Yamaha style setup, and what are the extra wires for?
And why does all the XS1100 wiring diagrams show an extra 8th wire, or is that merely grounding the body of the RR to the frame in addition to the ground wire?

So, calling on Geezer or other RR X-perts!!

Or, would be willing to trade/sell this RR for a non-1100 type in case someone needs one, I'm just using it on a 81KZ550A2 motor, and any 18+ amp 5-8 wire RR will do(except the Chinese junk)

Rich

[crazy steve]

...I'm pretty familiar with most RR's but the Yamaha's, I have an extra XS1100 RR and was wanting an explanation for the extra wires. It has what most RR's have, 3 stator and a hot and ground, now for the other 2, tan and dark green, the wiring diagram shows the tan going to the fuse box, same as the hot, is this a sense wire? And what is the purpose of the DkG wire, I'm assuming something to do with the fact these Yamaha's have a field coil separate from the stator.
The real question is, can I use this RR on a non-Yamaha style setup, and what are the extra wires for?
And why does all the XS1100 wiring diagrams show an extra 8th wire, or is that merely grounding the body of the RR to the frame in addition to the ground wire?...

Those 'extra' brown/dark green wires are what controls the output from the alternator. You'll find two basic types of alternators on motorcycles; a 'powered' rotor type (which is what the XS has) and a permanent-magnet-rotor type.

The latter operates at full output at all times, so to prevent overcharging the battery the 'extra' current is shunted to ground by the regulator. This is done internally at the regulator, so no additional wires are needed.

The 'powered' type varies the voltage/current to the rotor increasing/decreasing the strength of it's magnetic field, thereby controlling output from the stator. On typical alternators that have brushes/slip rings, this is done by varying the voltage into the rotor. One brush will have a wire connected, the other is grounded to the alternator housing.

The XS alternator is a variation on this design, but doesn't use brushes. Instead, the rotor is simply a chunk of metal that 'stirs' the magnetic field put out by the stationary 'field' coil and 'fools' the stator into 'seeing' a rotating field which then produces output. The brown wire is unregulated 12V power to the field coil and the dark green wire is technically a 'ground' wire, that by varying it's value changes the voltage/current through the field coil. If you take this wire to chassis ground, the alternator will go to full unregulated output.

So you have a brown wire (power to the 'rotor'), dark green (regulates the rotor), three whites (AC output from the stator), red (12V DC to the battery), and two grounds, for a total of eight wires. The extra 'free' wire shown on the diagram doesn't exist in reality.There is one more wire; a yellow wire comes off the stator and on the '78-79 bikes is used to energize the headlight relay coil. On the later bikes this wire is unused.

Could you use this regulator on another alternator? If it's a permanent-magnet type, no. If it's a slip ring/brushes type, you could use it if (and only if) both brushes are insulated from ground. Note that the XS regulator is designed for a 20 amp output alternator, trying to use it on one that has higher output will burn it up.

[old_skool]

Thanks, I appreciate the detailed explanation, and, it also answers the question, since I can't use it in my application, is there a thread on checking the values of these regulators before I offer it up for sale(SH233), as I won't be using it, and want to make sure it's good in the first place as I got it with spare parts and don't want to sell a possible bad one.
Thanks again Steve!
Rich

[crazy steve]

There's a detailed check procedure in the manual, but be aware you can't fully check one off the bike. You can bench check the rectifier diodes, but the 'regulator' part of it has to be tested on a running bike.

[old_skool]

I'll probably sell it conditionally that it's good or refund and trust the buyer.