AJS & Matchless Owners Club

Hi folks,
Newbie here with a '66 G2 CSR.
Bought the bike today and is in running/working condition

I am new to Brit bikes, have tinkered with classic cars and other bikes, but it is my first toe in the Brit scene.

The bike has a 12v conversion, and is running positive earth. I am not too sure on how it has been modified or the components used or why, so was hoping someone could offer some advice.

Here is a link to my google images account, i have always struggled with image sharing on forums, more so since the demise of photobucket.
https://photos.app.goo.gl/Rqv3BMW2xLdfoiZR9

It appears to be using a solid state rectifier (Wassell style?) but also incorporates a 2MC capacitor. The ammeter doesn't really swing, it flickers when the ignition switch is turned on ( goes to neg slightly) then hovers around zero when running.

I wonder if things are fighing each other? I have started unsheathing to get an idea, but wondered if anybody could shed some light on it. I want it as simple as possible really. Ideally negative earth (is there much involved in doing that with my current set up?), resistance wire delete and just plain old 12v. I assume that shouldn't require the capacitor? Hopefully the alternator isn't fried.

Any help is appreciated and thanks for such a smashing site. I've already spent many hours on here today and become a paid up member 🙌
Cheers

Callum

To run the 12v conversion it's been suggested by our harness supplier that a dedicated 12v harness is used as simply bypassing the resistance wire and installing capacitors etc is not the best long term solution.
The club now stock a special 12v conversion harness for this purpose.

Also you'd be better off with a modern reg/rec such as A Reg1 as it simplifies everything. It also does away with the zener diode (your's seems to be disconnected.)
Dave

Hi

I'm not sure why you have a capacitor in the circuit unless the bike was intended to be run without a battery. I would take the feeds from the alternator as they are, (three into two), and connect them to the regulator / rectifier. The DC output from the reg / rec can be fed to the bike as either positive or negative earth but be aware of the polarity sensitive devices which will need to be correctly connected: battery, coil, ammeter.

I see you also have a zener diode fitted but not connected - that will no longer be required either.

Welcome to the club

Regards Mick

Edited to add: MB8 40A is a bridge rectifier with no regulation - as above I suggest you purchase a combined regulator / rectifier

Edited to add: The points capacitor is also polarity sensitive

I assume the zener diode is the connector on the mudguard?

Yeah i've no idea what had been done, or more to the point, why.

Is there a diagram/instructions for how to wire the ignition switch? I have the wipac one and will do away with the emergency set up as suggested in the write up for 12v conversion.

I think i'll buy the podtronics reg/rec and go from there.

Thanks for the speedy responses already ✌️👌

Hi

Yes the zener is the lump fitted to the mudguard, it would have provided rudimentary regulation when connected.

Regards Mick

Strange that is didn't show a big charge on the ammeter with no zener connected??
Dave

Hi folks,
Currently elbows deep deciphering the wiring diagram and the current wiring.

Can we confirm that the orange and light green wires that go up to the ignition switch are now redundant, when fitting the 3 phase reg/rec? I assume once you splice in your three yellows to the three alternator wires, those are dead and don't do anything else? I am 99% sure that is the case.
I was going to use one of those wires as an alternative to the resistance wire is all.

Cheers!

A little extra...

Does anybody know which way the ammeter should be wired for negative earth, if there is no + or - on the case? I would assume just reversing the wires as they are, but seeing as it didn't move much before, i don't want to assume too much!

It'll be single phase unless you've changed the alternator. Only 4 wires to the reg/rec as Mick said. Yes a lot of wires are now redundant as you are not switching different coils in for lights etc. Full power goes to the reg/rec.
Dave.

I don't know if this guide will help you at all:
https://www.ifixit.com/Guide/AJS-Matchl ... ion/117790

Everyone's wiring setup is different these days, but there are some useful tips there (wiring diagram, etc.)