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Discussion Starter · #1 · (Edited)
Greetings from Norway!! We're new here. When I say we, I mean myself and my 14 year old son who is sitting beside me breathing down my neck hoping to get some answers and guidance from this forum about his new bike.

Having saved up for a bike he didn't go with modern plastic but chose this really cool cafe racer conversion of a '75 Cb 125 B6 twin. He can begin practicing for his liscense already next year.

We bought the bike despite it being advertised with charging issues. It took 5 minutes on Google to find out that all of these 6v electrical systems are dodgy at best. Sure enough after 15 minutes of tearing around on the bike...it's back to charging the battery.

Ok so a 12v conversion it is then and we started lurking on forums trying to get some answers. We came across what seemed like a creadible sourse on "Chop ...something".
It was said that this is the way to go forward:

1) change to a 12v battery - bought a Yuasa YB3L-B (12V 3.2Ah 30A)
2) install a cheap bridge rectifier - the bike already had one
3) Change all bulbs to 12v
4) put in a 15A main fuse
5) 12v flasher relay

It was also stated that the stator put out more than enough current to run this set-up and the coil was also ok.

Ok, so we did all this and the bike is still no better - even a little worse.
We measured the output at the battery terminals:

- at idle: 10-11.5V
- at 4000rpm: 12.2V
- at 9000rpm: 13v

So then back to charging the battery after a little tearing around!

Back to lurking on forums.

It was also suggested to splice the yellow and white wires from the stator together - we did this...no change :/

Ok, we need some help here! Hourly rates at bike shops here are north of 200dollars/hr so money saved by doing things ourselves is well spent on getting his liscence next year.
Can anyone tell us exactly which components from which bike can be installed onto this bike in order to make it into a reliable 12v conversion - with all the benefits of a 12v system.
We are not going to become experts in small engine electronics! Can you guys help us with a precise shopping list? It is my understanding that stators and other components are readily exchangable from Cb175, 200 and 350?

Any help would be greatly appreciated even though we're probably going to get yelled at for asking about what for most of you is I'm sure quite basic - or even worse...coverred earlier ;)

Cheers!!!
 

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Those numbers seem right, generally old Hondas run at a loss at idle.
The cb160,175,200,and350 stators are all the same size
It looks like youu should be able to bolt on a cb 160,175 or 200 stator with no modification or a cb350 with a little wotk.
The 350should have the highest output
 

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Greetings from Norway!! We're new here. When I say we, I mean myself and my 14 year old son who is sitting beside me breathing down my neck hoping to get some answers and guidance from this forum about his new bike.

Having saved up for a bike he didn't go with modern plastic but chose this really cool cafe racer conversion of a '75 Cb 125 B6 twin. He can begin practicing for his liscense already next year.

We bought the bike despite it being advertised with charging issues. It took 5 minutes on Google to find out that all of these 6v electrical systems are dodgy at best. Sure enough after 15 minutes of tearing around on the bike...it's back to charging the battery.

Ok so a 12v conversion it is then and we started lurking on forums trying to get some answers. We came across what seemed like a creadible sourse on "Chop ...something".
It was said that this is the way to go forward:

1) change to a 12v battery - bought a Yuasa YB3L-B (12V 3.2Ah 30A)
2) install a cheap bridge rectifier - the bike already had one
3) Change all bulbs to 12v
4) put in a 15A main fuse
5) 12v flasher relay

It was also stated that the stator put out more than enough current to run this set-up and the coil was also ok.
I did the same and messed about trying to get the original (CD175 6v) stator to charge a system upgraded to 12v.
LED bulbs to lower consumption etc.
Never worked well for me.

I bought a stator from a CL175, direct fit, problem solved.

I suggest looking on eBay for one of the breaker shops and buying a CB/CL175 stator.



Sent from my iPhone using Tapatalk
 

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Discussion Starter · #5 · (Edited)
Hi Simo and Alex, thanks for your responses!

Do we need anything else or should we try to only swap out the stator? I see mention of regulators - do we need one for this set-up? There are several vendors offerring stators and regulators together in a kit.
Will the new stator be connected into the same plug as the 6v unit? Or is there a need for modifying the output wiring? Do we continue having the yellow ang white wires spliced together?

Also about the coil...is there any truth to that the original 6v coil should be up for the task, or will it overheat? ...or just run it until it fries and then change it out to a 12v equivalent when the time comes?
 

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I used the original 6v coil pack for ages, no issues.

The wiring should be a direct swap out.
I added a modern regulator/rectifier so wired it up according to the (poor) instructions that came with it


If you want to burn some time you can see my stator change in my build thread

CD175 cafe racer - my first 4 stroke!

https://r.tapatalk.com/shareLink?sh...net/forums/showpost.php?p=402642&share_type=t


Sent from my iPhone using Tapatalk
 

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Discussion Starter · #8 · (Edited)
A direct swap out is music to my ears ;) I'll see if I can find a stator from a 160,175 or CB200. You say that they are the same physical size, but is the output higher on the 200 compared to the, say, 160?

When you guys are talking about a regulator/rectifier do you mean an ac/dc bridge rectifier? Like this:

https://www.e-deala.co.uk/5x-bridge...bpc3510-ac-to-dc-converter-200154.html#popup1

The bike already has one of these. Or is it this you mean:

Rick's Rectifier / Regulator Combo - Honda CB Twins

If it is the later you're refering to, looks like Rick's is a good one? If not only because of the promissed "installation guide" ;) (where exactly does the regulator/rectifier hook in)?
Does this 12v conversion still need an ac/dc bridge rectifier?


ALEX: now that was indeed time well burnt;) What a cool bike! Tidler looks like a true labour of love and you certainly have used a bucket load of time on it. I have a feeling that we'll often be refering back to your build as a reference!
 

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Discussion Starter · #11 ·
Simo: you mention the 35 dollar part from Sparkmoto - Is it the unit on the top right of the page? If yes...it's a single phase unit...but...

Alex: I see that on the top of your wiring diagram it says "2 phase".

Little confused. Can i use either?

Simo: does this unit replace the Ac/Dc bridge rectifier and gets plugged into the same plug?
 

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Greetings from Norway!! We're new here. When I say we, I mean myself and my 14 year old son who is sitting beside me breathing down my neck hoping to get some answers and guidance from this forum about his new bike.

Having saved up for a bike he didn't go with modern plastic but chose this really cool cafe racer conversion of a '75 Cb 125 B6 twin. He can begin practicing for his liscense already next year.

We bought the bike despite it being advertised with charging issues. It took 5 minutes on Google to find out that all of these 6v electrical systems are dodgy at best. Sure enough after 15 minutes of tearing around on the bike...it's back to charging the battery.

Ok so a 12v conversion it is then and we started lurking on forums trying to get some answers. We came across what seemed like a creadible sourse on "Chop ...something".
It was said that this is the way to go forward:

1) change to a 12v battery - bought a Yuasa YB3L-B (12V 3.2Ah 30A)
2) install a cheap bridge rectifier - the bike already had one
3) Change all bulbs to 12v
4) put in a 15A main fuse
5) 12v flasher relay

It was also stated that the stator put out more than enough current to run this set-up and the coil was also ok.

Ok, so we did all this and the bike is still no better - even a little worse.
We measured the output at the battery terminals:

  • at idle: 10-11.5V
  • at 4000rpm: 12.2V
  • at 9000rpm: 13v

So then back to charging the battery after a little tearing around!

Back to lurking on forums.

It was also suggested to splice the yellow and white wires from the stator together - we did this...no change :/

Ok, we need some help here! Hourly rates at bike shops here are north of 200dollars/hr so money saved by doing things ourselves is well spent on getting his liscence next year.
Can anyone tell us exactly which components from which bike can be installed onto this bike in order to make it into a reliable 12v conversion - with all the benefits of a 12v system.
We are not going to become experts in small engine electronics! Can you guys help us with a precise shopping list? It is my understanding that stators and other components are readily exchangable from Cb175, 200 and 350?

Any help would be greatly appreciated even though we're probably going to get yelled at for asking about what for most of you is I'm sure quite basic - or even worse...coverred earlier ;)

Cheers!!!
Hi,
Has the same motorcycle, Honda CB125B6 1975 Model. Struggling with charging and battery drained and engine stops. Have you got your order in order and what did you do to fix the charging problem? From what I can see in the drawings, there should be a voltage regulator, can this be a problem on these bikes? With regards from Norway.
 

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You could retain the 6 volt coil by adding a ballast resistor into the circuit
 

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The only real difference between a 12 volt coil and a 6 volt coil is the resistance in the primary winding windings. If you run a 6 volt coil on 12 volts there will be excessive current draw on the system, it will overheat the coil and shorten the life of the points, if you add resistance to the circuit the coil runs cooler and the points last longer. That's what car makers did in the 1950s when they updated their cars from 6 volts to 12 volts, adding a ballast resistor to the ignition circuit made the ignition parts last longer, and it was possible to incorporate a circuit to bypass that resistor while cranking the engine for hotter sparks and better starting. Ballast resistors are found on a lot of points era automobiles, also on Norton Commandos and some Honda Goldwings. Somewhat cheaper than buying a new 12 volt coil.
 

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You could retain the 6 volt coil by adding a ballast resistor into the circuit
The only real difference between a 12 volt coil and a 6 volt coil is the resistance in the primary winding windings. If you run a 6 volt coil on 12 volts there will be excessive current draw on the system, it will overheat the coil and shorten the life of the points, if you add resistance to the circuit the coil runs cooler and the points last longer. That's what car makers did in the 1950s when they updated their cars from 6 volts to 12 volts, adding a ballast resistor to the ignition circuit made the ignition parts last longer, and it was possible to incorporate a circuit to bypass that resistor while cranking the engine for hotter sparks and better starting. Ballast resistors are found on a lot of points era automobiles, also on Norton Commandos and some Honda Goldwings. Somewhat cheaper than buying a new 12 volt coil.
Thanks for the reply. Now I do not intend to rebuild the system to 12V. My problem is that the bike does not charge well enough. The bike starts and runs for 15 minutes and then the battery runs out. After charging the battery, the bike starts and works for another 15 minutes. I have switched to a new aftermarket coil (6V). When I remove the (+) cable on the battery when the motor is running, the motor does not stop, so this probably indicates that the stator is working. Could it be the new coil that drains the battery too much?
I had plans to convert to 12V, but have changed my mind.
 
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