Need some rectifier/regulator input from some gurus.

mmmboost

mmmboost

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I can fix engines, I can fab parts, I can build tools.......but electrical stuff is not my strong suit. Anything more than just basic wiring or similar is beyond my area of expertise so I'm hoping to enlist some help from the more experienced people on here.

I'm working on building a Cafe Racer out of my 78 XS400 and would like to replace the battery with a much smaller gel or AGM battery, however, everything I've read about them states that you need an upgraded solid-state rectifier/regulator in order to prevent damaging them from overcharging.

So here's where the question lies..... I have a rect/reg that I swapped out on my 2007 Suzuki GSX-R600 laying around and was wondering if it would be possible to use it. I've been studying the wiring diagrams, but they have different charging systems and I don't know if I can use this thing or not.

The rect/reg from the 'zuki has 7 wires coming out of it. 3 black (which go to the stator), 2 black w/ white stripe, and 2 black w/ red strip.

If someone could help me out I'd really appreciate it.

xs400f.JPG

K7 GSX-R600 Wiring Diagram.png
 
According to that diagram you can replace the stock rectifier with that reg/rec.
The 2 black/whites are your negative output, black/red your positive outputs.

You will need to keep the stock regulator or get an aftermarket replacement.

I'm in the middle of testing a similar setup with an aftermarket regulator but just had an unrelated carb problem so it's on hold.
 
Yeah I see that the rectifier portion would be fine there's really not much that as it's pretty simple circuit. I was just hoping this would kill two birds with one stone. I want a unit that is a rect/reg.


I just don't really know a lot about our charging system with the field coil and how I can deal with that.
 
That regulator/rectifier is the modern solid-state equipment you need to protect the battery from overcharging.

It doesn't do the function of the stock regulator. You need to keep the stock regulator. But it does do what you want it to do.
 
People do run AGM batteries with varying levels of success without putting in a modern reg/rec.

Just to reiterate, there are two things called "regulators"
There's the stock regulator that regulates the field coil. Putting it another way, they regulator the alternator input. With the stock alternator on these bikes you will always need a field coil regulator. Before you ask, there are no drop-in aftermarket alternators.
Then there are regulators off modern bikes that regulate the alternator output. This is what you talk about in the first post and what provides the overcharging protection.

Here's some info on an aftermarket replacement for the stock regulator (not a reg/rec):
http://www.xs400.com/threads/chargi...ltage-regulator-or-dead-charging-system.7567/
http://www.xs400.com/threads/where-to-buy-a-regulator.7557/#post-78728
There are other options available but that's probably the cheapest modern replacement for the stock regulator.
The one I was about to test is a Transpo IB301A.

Out of curiosity, what's the model # on the GSX reg/rec? SH640EB?
Trying out a CBR125 SH541QA reg/rec on my XS360 but it'd be good to know what other options there are.

To summarize: you need both.
 
Thank you for the clarification. I was under the impression that it was the regulator that was the issue. I am new to field coil alternators....only ever dealt with permanent magnet ones before. I thought the new solid-state combo units got rid of the old regulator and rectifier.

As far as batteries go, I was more interested in running a 4 or 8 cell lithium because they are so small. Very easy to hide in a seat pan or a seat hump. Unless of course you know of some small AGMs that I haven't been able to find on the Google.


The unit I have doesn't seem to have a model written on it, but I took it off my 2007 GSX-R600 when I was having electrical issues. I ended up buying a new stator and regulator because I didn't know which it was, so I ordered both. It ended up being the stator but I decided to put the new reg/rect on anyway so that's why I have an extra. The model on it would be 32800-21H00.
It looks exactly like this.
bd6044c262ce017b08508e653531e99c.jpg



So just to clarify, the voltage regulator on my bike is ONLY for the field coil?

And on the 'Zuki regulator, the 3 black go to the 3 yellow from the alternator, the B/W are ground, and the B/R go to the main fuse.....correct?
 
After reviewing the GSXR manual, I'm not sure this is going to work after all. The testing procedure for the regulator say to check voltage output at 5000 RPM and it should be within 14.0-15.5V. The Anti-Gravity Battery manual states that charging should never exceed 14.4V. Well shit... Now I'm not sure what to do

Here's the regulator/rectifier circuit.
suzuki regulator circuit.JPG
 

Attachments

  • GSX-R600-750K6.pdf
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Sooooo........ After MORE digging, I came across a thread on the Yamaha Triples forum and it looks like the XS750/XS850/XS1100 regulator/rectifiers might be exactly what I'm after!! I think I've even come across some MOSFET units!

Here's a photo of one of the guy's on there's regulator/rectifier. Looks like it has all the wires needed to work on the pre-CDI XS400's. 3x white from Stator, 1x black Ground (-), 1x red Main Fuse (+), and on the other connector 1x green Field Coil (+), and 1x brown Chassis Ground (-).
Wireing2.jpg


Source: http://yamaha-triples.org/forums/thread-view.asp?tid=15194&start=1

I've also included a wiring diagram and it looks VERY promising.
850g_wiring.jpg


xs1100 charging circuit.JPG
 
Last edited:
So I did a little testing on my bike when I got home. With the stock regulator and rectifier hooked up I'm seeing 13V at 1200 RPM. When I ramp up the revs, voltage across the battery leads caps out at about 14.55V. Seems like my charging system is in decent order. I'm still hesitant to try a LiFePo4 battery in there, but I read they are somewhat more tolerant to over-charging than LiPo. At least it won't explode under my ass while riding.
 
Can reply to more later.

That reg/reg may require some rewiring on the bike to work.
It's going to be an A-circuit regulator whereas your 1978 bike is wired as a B-circuit system.
 
BBS360 said:
Can reply to more later.

That reg/reg may require some rewiring on the bike to work.
It's going to be an A-circuit regulator whereas your 1978 bike is wired as a B-circuit system.
Click to expand...

How can you tell the different between A and B? I understand the difference between the two, but the wiring diagram looks indistinguishable to the XS400F diagram I've been using for my bike. (all the E versions seem to be crappy)

Edit: Nevermind I now see the difference after I drew out the charging systems on my own. The A-type have one side of the coil (black changes to brown at connector) going to the main switch (+) and the green wire going to the regulator.

The B-Type has the black wire going to ground and the green wire going to the regulator.
 
Last edited:
@BBS360.......so in order to change from an B to an A-type regulator all one would have to do is change the black wire at the field coil connector from black to brown and route it to the main power rather than to ground. Correct?
 
A stock regulator and rectifier from an xs400 does the job fine, for what it's worth. I ran a LiFePO4 with a stock setup. As long as you aren't running a mechanical regulator, and all wires/connectors are stout, there is no need to reinvent the wheel.
 
mmmboost said:
@BBS360.......so in order to change from an B to an A-type regulator all one would have to do is change the black wire at the field coil connector from black to brown and route it to the main power rather than to ground. Correct?
Click to expand...
That's what you'd have to do, but Wolfe is right. Ditch the mechanical. Go solid state.
In the other thread a Shorai battery was mentioned that can handle up to 15.2V.
Check out this thread:
http://www.xs400.com/threads/aftermarket-regulator-wiring.7479/
They don't mention it there but you might need to buy a pigtail connector to plug into that.
 
The shorai is what I got for both builds really happy withat it....granted I have a dohc with ss reg/rec...
But they are $$$
 
I know this was older, but im grateful for the wiring diagrams! I've a 78 xs400, and although they aren't technically for my year or model, they portray everything I need for simplifying and rewiring my bike. I'm great with wiring and electrical, so this post saved me a lot of time. I will stick to the 2 separate modules, however, I'm upgrading to SS voltage reg. and possibly getting a new rectifier.
 
Likely one is a supply wire and one is a sense wire.
Typically the supply would be as close to the battery as possible, in relation to fuses and switches, and the sense wire would be connected some place after the ignition switch, closer to the point of utilization.
It would help compensation for the voltage drop in the wires, switches, and 40 year old connectors.

But without knowing which is which just tie them together. Couldn't find an official wiring diagram for it that specifies.
 
After I purchase it, I will call the company and ask. If that is the case I'll find out which is which and hook it up accordingly with the assumption it will extend the battery life even if it is minute. If I feel lazy with everything else I need to do today, I'll just pigtail them together.
 

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