Ajs ignition

Information relating to the Matchless G2 or AJS Model 14 250cc Lightweight
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Ajs ignition

Postby Dixie1 » Tue Dec 01, 2020 10:02 pm

Hi everyone
I've just bought my first classic bike, a 1960 AJS 250 model 14 lightweight and have a problem which I hope someone can help me with. A few years ago it was converted to 12v and had a boyer ignition and power box fitted. It has a aftermarket switch fitted under the seat which isolates the battery and acts as a cut out switch for the engine. The ignition switch on the headlight seems to be permanantly live as even with the switch in the off position the bike will still start. I have swapped the switch with the headlight switch but is no different so iam assuming the switch is ok. Any help would be appreciated. Thanks Robert

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Re: Ajs ignition

Postby clive » Tue Dec 01, 2020 10:28 pm

Are you saying that the headlight switch is live and the bike will start even when the battery isolation switch is off? Or that with the isolation switch in the on position it does not matter what position the headlight switch is in? It sounds to me as thought the rewiring may have excluded the headlight switch from any relationship with the ignition.
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Re: Ajs ignition

Postby Dixie1 » Tue Dec 01, 2020 10:40 pm

With the isolation switch under the seat in the off position it cuts all power and wont start but with it in the on position everything works as it should apart from the ignition switch on the headlight and you can start the bike even when it is in the off position which also means you can't turn the bike off on the headlight switch.Sorry for any confusion.

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Re: Ajs ignition

Postby spookefoote1956 » Wed Dec 02, 2020 9:37 am

Sounds like they un-wired the ignition switch in favour of the cut out switch during the conversion. Probably to make sure that the cut out is used as a security feature.
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Re: Ajs ignition

Postby SPRIDDLER » Wed Dec 02, 2020 12:10 pm

Welcome to the club and forums Robert.
It may help for future posts if you include an approx location (e.g. county) in your Profile.

Dixie1 wrote:The ignition switch on the headlight seems to be permanantly live as even with the switch in the off position the bike will still start.

Evidently, if the headlight still works with your aftermarket battery isolating switch 'Off' it doesn't isolate the battery from the headlight.

I believe that in all circuit diagrams * for our bikes the stop light and hooter are shown as wired direct to the battery with a permanently live, unswitched, feed.
Perhaps the PO has wired all the lights in that circuit. :?

* There's a wiring dia. in your Owners Manual here:
http://archives.jampot.dk/book/Owners_m ... Manual.pdf
I poke badgers with spoons.....from 2 metres.

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Re: Ajs ignition

Postby Dixie1 » Wed Dec 02, 2020 2:32 pm

The isolation switch is straight from the battery so it cuts all power to everything. I would like to take this switch out which is straight forward but by doing this the only way to stop the engine would be to stall it which is why I would like to sort the ignition switch out which is on the headlight surround so it is working how it should and I would then be able to use this to stop the engine. Has anyone got a picture of how there switches are wired up with 12v boyur conversion or a diagram. Thanks

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Re: Ajs ignition

Postby dave16mct » Wed Dec 02, 2020 4:36 pm

I think it might be the Powerbox that's causing the problem. They're a great unit but they have a capacitor, so just isolating the battery won't stop it.
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Re: Ajs ignition

Postby Dixie1 » Wed Dec 02, 2020 8:08 pm

Hi dave isolating the battery does stop the engine. I have had a look at the ignition switch on the headlight casing and I have 3 wires coming from it. Brown goes to headlight switch, Blue goes to Ameter and dark green goes to black wire from power box. I thought maybe this was where the problem might be and the power box wasn't getting the right signal.

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Re: Ajs ignition

Postby Dixie1 » Wed Dec 02, 2020 8:17 pm

The green wire has a bridging wire going to the terminal next to it and a bridging wire going from the blue to Brown. Don't know if that's how its supposed to be. Thanks Robert.

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Re: Ajs ignition

Postby spookefoote1956 » Thu Dec 03, 2020 5:38 pm

Why have you got a powerbox and battery? My cub only has the powerbox.
हरे कृष्ण हरे कृष्ण
Hail Joe Lucas ............ Prince of Darkness!
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