Rectifier Swaps

[Skywalker]

Please forgive my newbie post.

I have a weak charging system on my 78 750. I know the right way to fix it is to swap in a Polaris or Shindengen R/R but before I knew what path to take, I bought a known-good rectifier from a 1981 750. My understanding is that this rectifier is also the regulator on that bike. It may not be the BEST fix, but I have it in hand, I really don't have the doe to explore other paths right now, and I want to use what I have.

This R/R has three yellow male bullet connectors, one red female bullet connector, and a black ground. Can I just plug this in the place of my old rectifier? If so, what gets plugs into what?

 

[posplayr]

Now we know Skywalker means "tight rope walking"

 

[Skywalker]

Now we know Skywalker means "tight rope walking"

Thanks for the input.

 

[tom203]

Let's follow this.... You know about the SH-775, so you must have done some reading here,but you want to carry on with a inferior substitute? Your 78 gs750 left factory with separate rectifier and regulator, does it still have this setup ?
have you seen this link and absorbed it ?
http://www.thegsresources.com/_foru...-Charging-System-Health&p=1138531#post1138531

Lots of clues! Courtesy of the humorist
beware that lots of these aftermarket r/r's are serious crap and if your stator is still good, why take chances.

 

[Skywalker]

Let's follow this.... You know about the SH-775, so you must have done some reading here,but you want to carry on with a inferior substitute? Your 78 gs750 left factory with separate rectifier and regulator, does it still have this setup ?
have you seen this link and absorbed it ?
http://www.thegsresources.com/_foru...-Charging-System-Health&p=1138531#post1138531

Lots of clues! Courtesy of the humorist
beware that lots of these aftermarket r/r's are serious crap and if your stator is still good, why take chances.

I have a 81 750 rectifier that I know is good. I want to use it to replace my original 78 rectifier and regulator. Simple. I've already stated that I know this isn't the BEST fix, but it's still better than what I have.

 

[Skywalker]

have you seen this link and absorbed it ?
http://www.thegsresources.com/_foru...-Charging-System-Health&p=1138531#post1138531

Lots of clues!

Actually, I thought that I had seen that, but had not. That does indeed help me a bit, I think. Thanks.

 

[tom203]

Your definition of "simple" is different than mine. There's more to fixing a suzuki charging system than attaching new parts. Read that link. Lots of us have had charging fun, best to avoid it if you can- stators are expensive, best to keep them happy!

 

[Skywalker]

So the 'replacement' R/R that I have that came from an 81 750, has one red wire, one back (ground), and three yellow. Is this not stock (an aftermarket)?

 

[Joe Guilbeau]

Here is an image of the 16-Valve GS750 engines generator out of the following Technical Service Manual for post 1978 models, I cannot quite determine the year that the manual was published.

Section- 6
Page - 1

http://www.mtsac.edu/~cliff/storage/gs/GS750_16valve.pdf

As you can see, the Regulator/Rectifier has three different colors to the unit...

White w/Red Tracer
yellow
White w/Black Tracer

Here are some images that might confirm the year model of your replacement, perhaps you have already verified this with an existing part number...

https://www.google.com/search?q=198...a=X&ei=H4NeVIbaPMueyAS-voKABw&ved=0CAcQ_AUoAg

 

[tom203]

So the 'replacement' R/R that I have that came from an 81 750, has one red wire, one back (ground), and three yellow. Is this not stock (an aftermarket)?

It's likely aftermarket- suzuki had an aversion to yellow stator wires, they liked multicolored ones. Any markings visible?
About how big is it?

 

[Guest]

The color code doesn't matter, red is 12V, black ground and the other three go to the stator wires. On the '78 you will find five wires from the factory stator. They split two of the wires for the separate rectifier and regulator. if you had the stator out of the bike you would see there is only three wires coming from the stator and further up the cable harness they soldered on additional wires for the split. I believe the wire colors are yellow and white/blue. The third wire that takes a trip from the stator through the light switch and back is white/green. Abandon one yellow wire, one white/blue and connect them and the white/green directly to the R/R wires. Ignore the color code from the R/R and stator. It doesn't matter which wires connect together as long as they are directly connected. Hook up the red from the R/R to the original 12v feed and run the black from the R/R to battery negative or a single point ground near the R/R. You will need to read up on creating a single point ground. It is recommended. Suzuki did a lousy job with that. That leaves a white/red and white/green wire left over. That is your loop through the light switch. They are not powered, so you can plug them together or tape them up to get them out of the way. Your diagram of the '78 system is not quite right, it's missing the second split. It doesn't matter you are abandoning the old split system and there are even odds that a stator change is needed. The modern series R/R hooks up the same way, it is a five wire system also.

 

[Skywalker]

The color code doesn't matter, red is 12V, black ground and the other three go to the stator wires. On the '78 you will find five wires from the factory stator. They split two of the wires for the separate rectifier and regulator. if you had the stator out of the bike you would see there is only three wires coming from the stator and further up the cable harness they soldered on additional wires for the split. I believe the wire colors are yellow and white/blue. The third wire that takes a trip from the stator through the light switch and back is white/green. Abandon one yellow wire, one white/blue and connect them and the white/green directly to the R/R wires. Ignore the color code from the R/R and stator. It doesn't matter which wires connect together as long as they are directly connected. Hook up the red from the R/R to the original 12v feed and run the black from the R/R to battery negative or a single point ground near the R/R. You will need to read up on creating a single point ground. It is recommended. Suzuki did a lousy job with that. That leaves a white/red and white/green wire left over. That is your loop through the light switch. They are not powered, so you can plug them together or tape them up to get them out of the way. Your diagram of the '78 system is not quite right, it's missing the second split. It doesn't matter you are abandoning the old split system and there are even odds that a stator change is needed. The modern series R/R hooks up the same way, it is a five wire system also.

Thank you very much. That is pretty much exactly the info that I needed! :frog:

 

[GS(X)400]

I have a 81 750 rectifier that I know is good.

None of them are "Good". There a part of the problem in the inherent design of the charging system. Replace it with the SH755 and have proper Single point grounding and a new good stator is the only way to improve the situation.

Sure it might work for few years with your 81 750 and that might be all you need out of the bike. But honestly if you expect any kind of longevity or reliability out of your bike spend the cash now and do it right.

 

[Skywalker]

The color code doesn't matter, red is 12V, black ground and the other three go to the stator wires.

Swapped the new-to-me R/R in this afternoon. Minimal improvements in mid RPMs, decent improvements at idle/low RPMs. While this wasn't a miracle cure, which I was not expecting, it was in fact still an improvement that took me from 'just barely squeaking by' to 'good enough for now'. I may look into a better fix at a later time, but I do want to say thanks again for the time and input.

 

[Steve]

Let me know if you need some in-person help. I am just up the road from you.

.

 

[Skywalker]

Let me know if you need some in-person help. I am just up the road from you.

.

Thanks Steve!