Later style reg/Rec Which one?

[NewHavenMike]

Ok so I've done some searching on my bikes electrical gizmos. My bike has two separate units, a nice little square one that will tuck away, and big cube. I want to simplify my wiring harness and keep it clean and factory.

I thought the later style rec/regs were one complete unit with two plugs coming from it? Im seeing ones on Ebay by the part number: 12R-81960-A1-00

Partzilla shows this as one piece, but when I type the part number on Ebay, i get the two units..

 

[NewHavenMike]

Ok, So I dug up my parts that came off my bike. The rectifier I have will work fine as it will tuck away nicely.

Rectifier P/N: 1L9-81970-60-00
The regulator I have is what I would like to change, without going aftermarket and able to work with a lithium battery.

Voltage Regulator P/N: 1L9-81910-50-00
For voltage regulators, Im seeing two different ones:

-2L0-81910-50-00, which came on 1978-82 XS400 SOHC
-12R-81960-A1-00, which was 1982 XS400J, and XS400RJ

I like how slim the 2L0 unit is, plus its factory. Motorcycle electronics are my weakest point guys and any help is appreciated.

One of my hobbies includes R/C planes, mostly everything is powered by lithium batteries. Im still on the fence with these batteries in a motorcycle. When we charge them, you need to put them in a fireproof bag because they can spontaneously combust and they need to be monitored and be balanced properly. Then, when they go dead, the voltage just drops off a cliff to nothing.

If I can find a small enough lead-acid battery ill take that. Ill just refrain from using the electric start...

 

[BBS360]

Rectifier P/N: 1L9-81970-60-00

You mention the rectifier then go on to talk about the regulator?

The regulator I have is what I would like to change, without going aftermarket and able to work with a lithium battery.

Stock regulators will charge to a higher voltage than most lithium batteries like. Lithium batteries didn't exist when these bikes were released. Lead-acid batteries can handle overcharging. Just add water.
As you know, overcharging lithium batteries kills them.

Voltage Regulator P/N: 1L9-81910-50-00
For voltage regulators, Im seeing two different ones:
-2L0-81910-50-00, which came on 1978-82 XS400 SOHC
-12R-81960-A1-00, which was 1982 XS400J, and XS400RJ
I like how slim the 2L0 unit is, plus its factory. Motorcycle electronics are my weakest point guys and any help is appreciated.

The 2L0 unit is stock for all but the earliest SOHC bikes. It does not rectify so an additional rectifier is required.
The 12R includes a built-in rectifier. Stock on dohc bikes.

Some members have had luck with lithium batteries but none of the stock charging components are truly suitable.
There has been some speculation lately that replacing the rectifier with one from a modern bike would add the electronic voltage regulation necessary to use lithium batteries without the risk of overcharging. A stock regulator (or equivalent aftermarket) would still be required to keep the alternator working.
Another option would be a full permanent magnet alternator conversion. Would require custom fabrication, a new rotor, stator, and regulator/rectifier anyways.

If I can find a small enough lead-acid battery ill take that. Ill just refrain from using the electric start...

Pretty small sealed lead acid batteries have been used. I think drewpy used one out of an emergency backup light.
E-start is lost. There is a risk of overcharging again since most of the backup batteries aren't meant for automotive charging systems. The modern regulator/rectifier swap may also help here.

I tried recently tried swapping in a reg/rec from a CBR125. Seemed to function at least but I haven't had a chance to test the voltage limiting.

In summary: lithium batteries usually bad with stock charging components.

 

[NewHavenMike]

Thanks for taking the time to clarify. This is getting me so confused for some reason.

Im fine with using the factory rectifier thats on my bike, I will have space under the seat and its slim enough to hide away.

I think im going to purchase the 2L0 unit. Its very small and they arent that expensive now, even new ones.. Now its just up to finding the right battery....