[Rnurmi]

Hi

My son is about to start building his firs bike. The project is a 1973 CB125K5. I 've been trying to seek for electronic ignition system to this bike, but I have not succeeded yet. Do you know any good sets available for this bike? There are something on Ebay that say they are fro CB125, but I cannot be sure are they really for twins. For example, Boyer 12v sets are available for bigger twins, but I have not found any 6V sets.

 

[Yendor]

Here you go.
I have this on both of my CB 350's

https://www.charlies-place.com/product-category/electronicignitions/

 

[Rnurmi]

But which set is for CB125K5? many CB125 models refer to CB125S, which is single. Secondly, US is not an option for purchase, unfortunately (the customs and taxes included over the price will lift the costs over the budget), unless the starting price is drop-dead-cheap.

 

[ajk4send]

There is only one contact per turn, as CB125K5 ignition is working in ,,wasted spark'' (Spark is created simultaneusly in both cylinders).

I think this is it:
https://www.charlies-place.com/shop/3-6-electronic-ignition-fits-64-69-s90-67-70-90-70-73-cbclsl100-73-75-cbcl125-66-69-ca160-dream-68-70-cacd175/

 

[Rnurmi]

Hi again.

I got some more info from other forums, so if anybody is dealing with the same issue, here is a couple of solutions.

The Boyer 6V British twin set that can be modified to fit in Honda
https://www.britishbikebits.com/boyer-micro-mkiv-igntion-kit-bsa-triumph-single-twin-6v

And here is a bit more expensive but well appreciated bolt on set
https://www.elektronik-sachse.de/sh...-cb125k-cb125j-cb125s-cb125-175-200-twin.html

The key point in these both is that they replace also the original advance, which I want to get rid of.

 

[Richard_Pitman]

Any more details of how the Boyer Brandsen ignition could be modified to fit ?

EDIT I tried emailing BB at [email protected], but this address was not recognised. I see that they list an ignition for the 250/350 twins, complete with a box that does away with the mechanical advance mechanism. You'd have thought that they could do something similar for the 175/200 engine.

 

[Rnurmi]

I can ask. I was only told that it can be modified. The CB250/350 and CB125/175/200 (200cc is actually odd size to me?) are quite different engines. The first one is 12V 180-degree twin with twin point system and latter 6V 360-degree twin with single point system. Boyer does not have bolt on set for smaller Honda twin, but this mentioned set fits to pretty much every British 6V singles and 360 degree twins which have single breaker point system. I believe it is all about modifying the assembly points in the breaker box.

 

[Simo]

Hi and welcome
Since you're modifying the electrics, why worry about finding a 6v system just upgrade to 12v
Your slightly wrong about which twins are 6v/12v
All cb250/350 are 12v The cb/cl175 and 200 are 12v, the cb 125 and CD175 are 6v
The stator in most small Hondas are interchangeable ( you can put a cb360 stator in a late 60's ct90) if they're close in vintage.
Why are you worried about the mechanical advance?

 

[Richard_Pitman]

And we obviously knew the difference between the twin coil and points 250/350 engines 180-degree engines, and the single coil and points 125/160/175/200 360-degree engines, but I'd have guessed that there wouldn't actually be much difference in the advance curve of these engines, and for me, the idea of replacing the mechanical advance with electronics quite appeals. For no other reason than I like tinkering with things …

Just following a few links:

https://www.britishbikebits.com/wassell-vape-igntion-kit-triumph-bsa-norton

http://www.grintriumph.com/images/Electrical/WasselIgnition/WW61495.pdf

 

[Simo]

And we obviously knew the difference between the twin coil and points 250/350 engines 180-degree engines, and the single coil and points 125/160/175/200 360-degree engines, but I'd have guessed that there wouldn't actually be much difference in the advance curve of these engines, and for me, the idea of replacing the mechanical advance with electronics quite appeals. For no other reason than I like tinkering with things …

Just following a few links:

https://www.britishbikebits.com/wassell-vape-igntion-kit-triumph-bsa-norton

http://www.grintriumph.com/images/Electrical/WasselIgnition/WW61495.pdf

Yes I get the tinkering bit, I have toyed with putting a black box on as well, but only so that the timing could be crank driven, getting rid of the cam chain slop/strech ( I'm pretty confident this is why it's almost impossible to get the both side to fire exactly on F) As for the curve on the 175 it's probably a pretty flat line between 1200rpm which has no advance and full advance at 5000rpm. The only Honda document I've seen is this cb175 add.
Unfortunately google has never had a big enough version and I've never found a print copy