Suzuki GS450E Overcharge

[ChickenStorm]

Hi! I've recently redid the whole wiring harness and installed full LED lights and a new battery. The issue I'm running into is very high charging voltage at the battery. I measured around 19V at idle with the lights off, 17V with the headlight only since the tail lights weren't plugged in at the time. I couldn't manage measuring at revs since my multimeters prongs didn't want to stay in place. This will cook the battery so any suggestions as to what I should do? I was thinking about installing a resistor on the output wire as to bring back the lost load from the old lights, but I don't know if this is feasible at all. The wires coming off the stator are all yellow, and so are the wires from the rectifier/regulator before the plug, in the middle the wires are separately coloured which is odd. Thanks!

 

[Nessism]

Clean your R/R ground, and move it to a solid frame point, not the battery box. If that doesn't work, get an SH775 and rewire the entire charging system

 

[ChickenStorm]

Thanks for replying, I actually moved the ground directly to the battery negative and no luck there either. Does a new one have to be the SH775 or would any three phase R/R work, even for just a while?

 

[Nessism]

Any three phase R/R will work. If this bike is a keeper, get the SH775, though. It helps protect your stator from over heat failure. They are no more expensive than other R/R's, so why not?

https://www.ebay.com/itm/196209810000

 

[Rob S.]

Ness, don't you have one you could sell him?

Chicken, if Nessim sells you one, he's already tested it. Welcome to the site.

 

[Nessism]

Ness, don't you have one you could sell him?

Chicken, if Nessim sells you one, he's already tested it. Welcome to the site.

Yes, I have pre tested SH775's that I sell. After seeing the photos of the bike in question, I made the assumption that the OP is a DIY type, and looking to save pennies where he can...and that means taking a gamble on a cheap eBay R/R. In truth, the SH775 is very reliable, so the biggest risk with buying used is getting one that's got a busted connector. You don't even need to buy a fancy connector. Using common spade terminals, with an RTV seal over the top, works just fine.

 

[oldGSfan]

Yes, I have pre tested SH775's that I sell. After seeing the photos of the bike in question, I made the assumption that the OP is a DIY type, and looking to save pennies where he can...and that means taking a gamble on a cheap eBay R/R. In truth, the SH775 is very reliable, so the biggest risk with buying used is getting one that's got a busted connector. You don't even need to buy a fancy connector. Using common spade terminals, with an RTV seal over the top, works just fine.

Hey Ed... Not to sidetrack too much but the 'go to' on British bikes to replace the eminently reliable Lucas zener diode and rectifier is a 'Podtronics' unit. It's about $50 and they make single and 3 phase. I'm running the latter with a new 180W alternator on my Norton. There's hardly any load on it with electronic ignition (no more magneto!) and a headlight and taillight and horn. They market toward British bikes very successfully, and I'm sorta wondering if it's just a Chinese unit you can buy off Amazon? I helped a friend get his Vietnam (OMG the wiring horrors!) '67 Vespa to charge and used a $13 Amazon 'RUTU 4 Wire full wave Universal Voltage Regulator Rectifier' after some research, and it has been working fine for a couple of years now. Maybe I gotta read the Stator Papers but I have been super lucky with the 6 GSs I've owned over the years, never a charging problem. My next GS may need one!

I'm curious how the SH775 came to be the 'go to' for not just GS's but I think for other Japanese bikes from the same era - it sure seems to be a quality unit from what I've read, and perhaps user experience has elevated it - whereas the Podtronics may be just targeted marketing and low expectations.

 

[ChickenStorm]

Thank you for all the replies! I'm now wondering if for example I were to install an inline DC to DC regulator after the R/R to properly step down the output voltage, would this be dangerous for the R/R or stator? I'm quite confident in my soldering so making a simple 18V-12V regulator in a small form factor is not at all impossible, I'm just wondering if there are any risks with this approach?

 

[ChickenStorm]

Also what kind of current is the charging system capable of producing at peak output?

 

[Nessism]

Thank you for all the replies! I'm now wondering if for example I were to install an inline DC to DC regulator after the R/R to properly step down the output voltage, would this be dangerous for the R/R or stator? I'm quite confident in my soldering so making a simple 18V-12V regulator in a small form factor is not at all impossible, I'm just wondering if there are any risks with this approach?

Why try to engineer your own solution, when you can buy a decent used motorcycle R/R for dirt cheap? I just noticed that you are in Finland, so maybe visit your local motorcycle junk yard and buy an old Honda Shindengen unit? They are super reliable, and widely available.

And if you really want to fix the system, rewire to eliminate the stator loop wiring. That's widely know to cause problems. There is countless information about that in older posts here.

 

[unfocused]

Also what kind of current is the charging system capable of producing at peak output?

A broken one...

One thing to make sure is your battery isn't already dry - this will make a charging system to crazy things.

 

[Cipher]

at 19v your regulator is clearly dead. Replace with the suggested reg rect and never experience this again.
did your battery boil dry?

 

[ChickenStorm]

Ok so big update, I figured out the issue. The previous owner had replaced the regulator with a different six pin model (NSR 40 in sharpie on the back) and had wired the extra black wire straight to ground. I did some research and found out that the black wire is meant to have a 12V input from the ignition switch to energise the regulator circuit. I spliced the black wire into a switched 12V supply and like magic, 14V to the battery regardless of rpm! Bummer is I already ordered a used R/R and it was shipped today from a private seller so atleast I've got a spare. Thank you all so much for the advice, I will surely keep you guys updated as I go along with this project!

PS. Is there a way for me to upload pdf documents and such on my posts? I have some schematics and gasket surfaces I've modelled that might be useful, for instance I've got models for cutting your own float bowl gaskets

 

[Rich82GS750TZ]

Good for you.
As for files and such- we have a companion site called BikeCliff’s website. Long story, short. Cliff isn’t involved anymore, so bwringer made a copy and maintains it with gads of GS knowledge. The link to the site is in my signature. Brian may be interested in putting your files up on that site. You can probably PM him or find his email address by clinking on his username.

 

[Cipher]

Ok so big update, I figured out the issue. The previous owner had replaced the regulator with a different six pin model (NSR 40 in sharpie on the back) and had wired the extra black wire straight to ground. I did some research and found out that the black wire is meant to have a 12V input from the ignition switch to energise the regulator circuit. I spliced the black wire into a switched 12V supply and like magic, 14V to the battery regardless of rpm! Bummer is I already ordered a used R/R and it was shipped today from a private seller so atleast I've got a spare. Thank you all so much for the advice, I will surely keep you guys updated as I go along with this project!

PS. Is there a way for me to upload pdf documents and such on my posts? I have some schematics and gasket surfaces I've modelled that might be useful, for instance I've got models for cutting your own float bowl gaskets

Well its good its fixed but if its an OEM suzuki piece it will die. But pushing a motorcycle is good exercise.
If the part you orders is a sh775 install it when it comes.

 

[Cipher]

Well its good its fixed but if its an OEM suzuki piece it will die. But pushing a motorcycle is good exercise.
If the part you orders is a sh775 install it when it comes.
I had three regulators die in a new bike in the 80s. The last one lasted for years but the first and second died quickly.
iirc they were 275 CAD a pop and with my trusty inflation calc that means crap suzuki electrics cost me:
$550 in 1985 is worth $1,386.90 today

What a sickening realization.​

 

[ChickenStorm]

Why does the GS charging system seem to kill R/R so regularly? Is there a specific design choice causing them to fail?

 

[Cipher]

Why does the GS charging system seem to kill R/R so regularly? Is there a specific design choice causing them to fail?

There's a link to the stator papers somewhere on here.

 

[Nessism]

Why does the GS charging system seem to kill R/R so regularly? Is there a specific design choice causing them to fail?

I think Suzuki cheaped out on the R/R's they bought. They were small, thus they couldn't dissipate much heat. I also think their generators made too much power. And when using a common shunt type R/R, that means that all the unused power got sent back to the stator, where it was converted to HEAT, which burned it out.