AJS & Matchless Owners Club

Hi i am new to this just bough a 1957 16MS. Generally in good nic but electrics are a bit of a mess =. 12v electronic everthing works except no charge when running. Battery is new, any pointers please
Thanks Nick

I would start by checking the output from the dynamo. Join terminals F and D together and connect to one side of a bulb or meter. Connect the other side to earth. The bulb should light when the bike is started if the dynamo is charging (or the output should show on the meter.) Other things to look for : has a fuse from the regulator to ammeter blown? Is the earth point clean and bright? Are the nuts on the ammeter contacts loose? Other loose or bad connections. What type of regulator is it?
Dave

Welcome to the website!
Wot Dave said above, plus there's a wealth of info (including wiring diagrams) in the factory manuals in the link below. Bear in mind that apart from the cosmetics your AJS 16MS is identical to the Matchless G3LS.

See here under 'Books'........

http://archives.jampot.dk/

Thanks guys also found the battery is discharging so have leak to earth as well.

Nick1957 wrote: ↑Mon Apr 08, 2024 12:58 pm Thanks guys also found the battery is discharging so have leak to earth as well.

My immediate suspicion would be the voltage control unit. Not sure if 57 is dynamo or alernator. If dynamo and its been uprated to 12 volts some of the early electronic voltage control did not cut off the circuit when the revs dropped. This does not cause too much of an issue in use (unless as i have to you are driving around at 20mph constantly!) However if the bike is left for a week or two the battery will flaten as the power leaks back to earth via the field windings. The solution is to fit an on off switch or to take the fuse out when leaving the bike parked for a long period. Not really necessary whilst out and about as the drain is relatively slow.
Not sure if the same holds for alternator models but i suspect it does as i have had the same issue with aftermarket alternator replacements for the dynamo.

Obviusly detected leak needs tracing but I'd also check the ammeter is functioning..I've got a sticky one that doesn't always tell the truth.

1957 bike should have a dynamo but if it has been uprated to 12v is the regulator polarity the same as the dynamo?

It may be worth going back to basics and checking that the battery connection, regulator and dynamo are all the same polarity. The regulator should be marked either positive or negative earth and your battery should match that.
Originally it would have been positive earth so the positive terminal on the battery should be connected to a good earth on the frame. The earth lead wire from the regulator should also be connected to the same earth point.
If this is all Ok then the two wires should be removed from the dynamo and the field (F) terminal on the dynamo should be momentarily connected to the negative (live) terminal on the battery.
Make sure that the dynamo wires are reconnected with the F & D terminals going to the same terminals on the regulator.

If after doing the above there is still no charge, you can check the dynamo is working by doing the checks that dave16mct suggested.

If there is an output it would suggest either a regulator or wiring fault.
As previously posts have suggested, earlier electronic regulators were not up to scratch, which could account for your drain to earth, and I think that the more modern Wassel device also requires wiring modifications in the dynamo for positive earth operation. If your dynamo is Ok and you are confident in the wiring then I would scrap anything other than a DVR2 regulator.

There's an excellent practical guide with diagrams on testing the dynamo here:

https://www.matchlessclueless.com/elect ... as-dynamo/