1981 rec/reg


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I see a lot of talk about the charging system on these and was curious. How do I tell what kind of rec/reg I have? From my understanding, there’s a solid state one and...an.. older one? If I have the solid state, would that support a LiPo battery? I wanna cafe my 81 xs400h (I think that’s the right model. Has drum brakes)
It'll have a solid state regulator. Rectifiers are the same for all single-overhead cam years (black with fins).
Looks like this:
Piggy backing on this thread, but what is the correct replacement regulator for this? My '79 has this same reg and I think it's dead.

Im currently using a Antigravity 4 cell with my bike. I use an aftermarket car regulator that I had to wire myself.

The problem is the older mechanical ones. The stock solid state regs are fine if they work. Its the newer technology batteries that cant take the variable charge rate.

With that said, I started using this 4 cell battery this year, so I have no idea how long it will last. I have a volt gauge on my bike and lately thats been giving me high voltage readings, like around 14.8 at all times no matter if I have every light on or not. The tail light is LED and acts as a runner, brake, and tag light. Im keeping an eye on the battery, its gotta be overloading and greatly reducing lifespan.. I do not know yet.

The regulator I use is the R292 from BWD, Borg Warner also makes the same one. I am not sure if it is compatible, or makes a difference if your bike came stock with a solid state reg. My 76 had a mechanical one so this was a nice upgrade for me.
@BBS360 I'm getting a bit confused as it sounds like only '80+ had a solid regulator but my '79 has it. The R292 has 4 wires but my stock solid only has 3 like the VR125.

I'm so confused.
Over On the XS650 site a lot of us have been using a Fiat regulator. A VR794. It fits a 79-80 124 Spider and X1-9.
It works well with the 80 and later bikes. I have an 80 and later alternator on my 75. It charges a steady 14.2 volts.
It comes with a grown and green wire. The brown hooks to Power after the switch. This wire reads the voltage, so you want it as close to the battery as you can get. Just after the switch to be sure it won't drain the battery if it sets very long.
The Green wire Goes to one side of the field coil, the other side of field coil to power after the switch.
The field coil gets power from the battery.
The case needs a good ground.
It's not very big. About 2.75 inches to the outside of the mounting tabs, about 1.5 inches at the widest, .75 inches thick.
I paid $27.61 for two including shipping. I bought these In April of 2018. I don't think the price has changed much.
If your Rectifier is bad I can recommend a replacement for that too. On Ebay search for Three Phase Rectifier. Used a lot in wind power.
They handle most any voltage. Most rated like 600 volts. That's not the big thing. The amp rating is. Your charging system puts out around 16 amp. So any thing rated at least 25 will serve you well. Most have an aluminum case that they use for a heat sink. Some of the higher rated use a large finned case.
Easy to hook in. They come with % terminals Three hook to the stator wires. These have a wavy emblem by them. The other two have the DC out put They have a DC emblems by them. Mount so the case is in good contact with what ever you mount it too to help dissipate the heat.
I can't seem to find my receipt for them but they weren't much. Like $5 sipped.
I have pics. One is the reg, the other two are rects. one plain, one with fins.


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  • 3 phase rectifier with big heat sink.jpg
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I think with the right wiring changes these can work on the older bikes with a mechanical reg.