[1982 Honda CB125S] Need help with rectifier/regulator for a 12v conversion.

[RoyalRider]

Hi everyone,

I have a '82 CB125S that I am working on and planning on turning into a nice little Cafe. I have done some work on it already and hope to make a detailed post over in the projects section once it is completed. When I bought it, it did not run and did not have front brakes. I have since returned the engine to running condition with a new carb and have replaced the front brake cable, front and rear brake drum shoes, installed new clutch plates, and installed a new gasket on the clutch side engine case.

I have already read the guides that other dudes have posted here on how to do a 12v conversion but most of them are for the 70s era version. They have different regulator/rectifier units and no CDI pulse generator like mine does.

Here is my problem and what I need help with : the original rectifier/regulator has 5 wires leaving it and my new rectifier only has 4 prongs for wires to be installed.

Here are pictures of the old R/R with the new R/R as well as a picture of my bike's wiring diagram : http://imgur.com/a/RZt8K#0

I was hoping to cut the wires coming out of the old R/R and fabricate some prong-type connectors to reconnect them to the new R/R so they can connect to the original wiring loom.

As you can see the yellow and pink wires come from the alternator. I can't join them together and place them on the 4th prong as that might short out the alternator (or so I was told. I am very bad at electrical business so please bear with me).

My guess is that one of these 5 wires can probably act as a ground and might not need to be connected to the new R/R unit. I need to figure out which one but I suck at everything electrical...

Furthermore, I am not sure how the internal wiring of the new R/R unit works and if it even matters. The new R/R was purchased from Ebay and has zero information other than it's a silicon based model and was meant for small displacement scooters/motorcycles up to I believe 150cc.

This diagram : http://i905.photobucket.com/albums/ac258/bashan_2010/Technical_2/Rectifier_Pin_Out-1-1.jpg supposedly shows the inner workings of the R/R but in the same thread that this diagram was posted someone mentioned that the top left yellow can sometimes be switched with the top right red.

I have tried to use my multimeter to test out the R/R according to this diagram and am not getting readings...it's possible I waited a month for this R/R to arrive and it's a complete dud.

Any help is much appreciated, I understand that these sort of gremlins are not easy to get rid of and without being to see what I'm working with it might be hard to help me out. I'll take anything I can get because without the lights working I can't pass safety with this bike which is keeping me from doing any major work on the project.

Thanks for reading

 

[RoyalRider]

Did some more research and this thread : http://buggynews.com/blew-another-gy6-regulator-rectifier-t19227.html?mobile=on discusses the "ebay R/R" that are available. They say that the one without fins on the side like mine is a 110cc R/R that can supposedly be half-wave or full-wave depending on whether or not it's frame grounded or not.

Here is the, I'm guessing, schematic for the R/R I purchased

 

[RoyalRider]

I have received a bit more info from someone on another forum. They noticed that the schematic for the rectifier I have shows a single diode D1, so it would be a single phase half wave regulator.

He says the internal schematic of the 150cc GY6 regulator shows a single phase full wave rectifier consisting of diodes D4 through D7 and that both ends your stator could conceivably be connected across the full wave rectifier of the 150cc unit...

Here's the schematic of the GY6 and a picture of it : http://imgur.com/a/KpDKd

Does that sound like it makes sense? I'm sorry I'm no good at reading the schematics.

 

[DohcBikes]

Yes this makes some sense. The reg/rec you purchased has a half wave rectifier. You don't want this if your alternator is putting out a full wave. And it probably is, unless it is three phase which I doubt.

Your first link is blank for me so I don't have the cb125 diagram or the old reg rec diagram but the simple solution is to obtain a full wave reg/rec. These can be 4 wire or five wire, and almost any full wave reg rec will work so if you have any laying around from old projects that's what I'd use.

 

[RoyalRider]

Hi DohcBikes thanks for the reply,

Here is a re-upload of the first album so you can hopefully see the pictures. I've included two seperate links to hopefully insure you see them : http://imgur.com/a/PIgO5

http://postimg.org/gallery/tvhutp0q/

I don't have any extras lying around but I can go ahead and purchase the GY6 one which is full-wave. The most commonly available one has 4 prongs so what do I do in that case since I still have 5 wires to connect? I assume one of them will be left-out and possibly grounded to the frame?

 

[Sonreir]

The unit we sell will work for you.

http://www.sparckmoto.com/products

 

[DohcBikes]

Great opportunity to support a member. Thanks for the link sonreir, you'll be seeing some orders from Dohc at SouthCycle in the near future.

RoyalRider, how bout just ordering one from sparckmoto, its a perfect fit for your application.

 

[RoyalRider]

Holy shit Sparck to the rescue!!!

Amazing this will work perfectly.

Can't thank you guys enough for reading and helping out.



EDIT

Just put in an order now through your site