Ariel Owners Motorcycle Club

Hi Bruce

That's positive, (no pun intended). Do you have a multi meter, or can you borrow one? Set it to Volts DC and connect it to the battery terminals, (red to positive), it should read six volts or slightly less when the lights are on and engine off. With the lights on and the engine revving slightly it should read over six volts, if this is so then all seems OK. If, with the engine running the battery reads below six then you probably need to investigate the regulator, please report back again.

Regards Mick

So, here is the state of play, which is giving me sleepless night !!
With the engine running and revs high, the voltage across the battery does not go above 6 volts. Furthermore, the lights do not brighten either.
I have once again tested the dyno, by bridging out the terminals and measuring the voltage to earth. It is way above 6 volts depending on the revs, so all seems to be good there.
First question.
Which of those terminals on the dyno are for the "F" and "D" wires to the regulator, ie is the lower one or higher one "F". Does it not matter?
I have replaced to regulator with a "new" one I bought several years ago. It was still in it's box. How can I test it. Making sure that the "F" and "D" wires are well connected, can I test the output from the "A" terminal, which appears to be one one carrying the current to the lighting switch, for distribution to the ammeter and back to the battery?
In my limited electrical knowledge, I am trying to following the flow of the current, testing each part, to hopefully find the fault. A bit like canoeing down a river trying to find the beaver dam !!!!

Hi

It does matter which way you connect F and D, I'm not sure which type of dynamo you have but the Brightsparks website has a good online Lucas library so you can look it up for yourself. See what happens when you are sure F and D are correctly connected, who is the regulator manufacturer?

https://library.brightsparkmagnetos.com ... /index.htm

Regards Mick

The voltage on the D wire, which is the lower terminal, is the dynamos output voltage. It splits into two; one wire goes to the bulb in the ammeter, the other goes to the regulator.
Initially D is connected directly to F; which is the upper terminal; by a closed contact, inside the regulator.
If you connect a voltmeter between D or F, and any bare metal on the engine, you should get exactly the same result as connecting a piece of wire between D and F.
Let us know what happens.

Hi There,
The regulator is a no name brand supplied by Wassel Motorcycles.
It was many years ago and I see that this model WW 10208 does not exist anymore in their parts list. You can buy something that looks very similar with the model no. MCR2 37097. Feked Ltd sell a Lucas one for a whopping £84 !!
Now, whether I bought the correct one for a SQ4 ( +ve earth ) I have no idea. Can you buy an incorrect 6v regulator?
I will hit it once again with my trusty Avometer over the weekend.
Chrs
Bruce

hi Bruce ;
those indian made MCR2 regulators are absolute junk , dont use one , it wont last very long at all .
they have steel terminal strip for starters unlike the original lucas brass ones .
i made a mistake and bought a "new" MCR2 and fitted it , and it did work for about 2 hours total .
when first fitted to bike it worked , but after i had been out for the first ride on it everything stopped charging again .
in end i got an AO services Vreg and i fitted it inside my old lucas MCR2 box , all the wires were same colour for FADE and i soldered them to the terminals in the mcr2 box , i had already dismantled the coils etc in the box and used the aluminium plate to mount the AO voltage regulator to it inside so it all looks like the original regulator externally .
the dynamo wires all go back into the terminal strip on the regulator using the same RIPAULTS wire terminals which i soldered up and also used the original terminal retaining strip that you have to push the wires through before soldering terminals on and screws on to hold the wires in

can get the whole range of old style wiring terminals here in the link to stafford vehicle wiring , scroll to lower of page

https://www.s-v-c.co.uk/categories/staf ... -terminals

hope you sort it out soon .
ian

Hi

I would agree with the above, slave in an electronic regulator and see what happens, if your problems disappear then consider how you want to move forward. Hide the regulator inside the MCR2 box or find a reliable old style regulator, (not easy or cheap), I'd go for electronic.

Regards Mick

You have convinced me.
Thks guys.

Mick D wrote: Fri Mar 06, 2026 8:20 am I would agree with the above, slave in an electronic regulator and see what happens, if your problems disappear then consider how you want to move forward. Hide the regulator inside the MCR2 box or find a reliable old style regulator, (not easy or cheap), I'd go for electronic.

I agree, I've got AO regulators on all my bikes and have had for years. Great product. People rate the DVR2 one as well, though I haven't used that personally.