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Auto advance ADT unit

Posted by Brickboy on March 7, 2025, 6:04 pm

Investigating the lack of go above 50mph on my AJS I discovered that the auto advance unit on the SR1 mag is worn and the slop in the internal shaft when acted on by the pull of the drive chain locks up the advance mechanism. Bit of a sod!

Feked sell new ones for... £324!!

Anyone know a good restorer of ATD units? I'll give Priory Magnetos a shout but wondered if anyone knows any other clever people!!

Re: Auto advance ADT unit

Posted by ChazzyB on March 7, 2025, 6:12 pm, in reply to "Auto advance ADT unit "

Thorspark have an SR1 electronic ignition kit. £150

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Re: Auto advance ADT unit

Posted by ChazzyB on March 7, 2025, 6:15 pm, in reply to "Re: Auto advance ADT unit "

Or find an N1 mag with manual A/R.

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Re: Auto advance ADT unit

Posted by Brickboy on March 7, 2025, 6:30 pm, in reply to "Re: Auto advance ADT unit "

Thanks Chazzy. I'd prefer to stay trad but at that price it's tempting!!

Re: Auto advance ADT unit

Posted by ChazzyB on March 7, 2025, 6:40 pm, in reply to "Re: Auto advance ADT unit "

And probably a lot more reliable.

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Re: Auto advance ADT unit

Posted by Brickboy on March 7, 2025, 7:22 pm, in reply to "Re: Auto advance ADT unit "

Non starter sadly, Chazzy. They use the original advance/retard unit which is what is knackered. The mag has been rebuilt by Tony Cooper so it's sound and has a great spark. It's the ATD that's knackered

Re: Auto advance ADT unit

Posted by ChazzyB on March 7, 2025, 7:36 pm, in reply to "Re: Auto advance ADT unit "

Match, gallon of petrol...

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Re: Auto advance ADT unit

Posted by Brickboy on March 7, 2025, 8:16 pm, in reply to "Re: Auto advance ADT unit "

At the moment I wouldn't want to waste a whole gallon on it.

Actually, I really do like it even if the previous owner has cut far too many corners perhaps even been disingenuous. Still, it's a joy to ride, idles perfectly and starts first kick. I just hope the engine internals have received better quality work than the finishing off did. There's a story behind it but I'm not really enamoured of the previous owner. Still, we've all been there.

Re: Auto advance ADT unit

Posted by geoff the bonnie on March 7, 2025, 9:11 pm, in reply to "Re: Auto advance ADT unit "

If it helps the sorrow, you can burn it much slower by using diesel as an accelerant

Re: Auto advance ADT unit

Posted by ChazzyB on March 7, 2025, 10:11 pm, in reply to "Re: Auto advance ADT unit "

Ah, the constant joys and delights of owning an old bike. I'm in the throes of one such delight with my own 18S at the moment.

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Re: Auto advance ADT unit

Posted by Tonupdave on March 8, 2025, 8:52 am, in reply to "Re: Auto advance ADT unit "

My AJS had a manual same as the Ariel the only thing that ca go wrong in that department is cable breaking

Tonupdave..T.U.D.

Re: Auto advance ADT unit

Posted by Andy C on March 8, 2025, 9:06 am, in reply to "Re: Auto advance ADT unit "

Do I detect cracks starting to appear ?

I nearly gave up on the KH but I have now sunk too much time / effort into it to get rid of.

Hopefully the work I did over winter will deliver what I expect from the bike.

Used bikes epsecially older ones are always going to have issues.

I tend to stick with them and fix them up, but have told me the KH will be the last ever fixer upper, although I might make an exception if a decent MZ ETZ 250 or 301 appears.

Think I would go for the solid state option in your case, as it is cheaper, and is probably going to be more reliable - you can always keep the old unit to sell with the bike when you move it on.

Who needs a signature anyway......

Re: Auto advance ADT unit

Posted by 6TDen on March 8, 2025, 8:15 am, in reply to "Re: Auto advance ADT unit "

Or you could swap it for a Triumph 6T in working order, currently.
Den

Re: Auto advance ADT unit

Posted by geoff the bonnie on March 8, 2025, 8:16 am, in reply to "Re: Auto advance ADT unit "

Den, that Thunderbird is now worth 5 Franks running

Re: Auto advance ADT unit

Posted by 6TDen on March 8, 2025, 9:18 am, in reply to "Re: Auto advance ADT unit "

REALLY !!!!!

Re: Auto advance ADT unit

Posted by Jimbo on March 8, 2025, 10:22 am, in reply to "Auto advance ADT unit "

Re: Auto advance ADT unit

Posted by Jimbo on March 8, 2025, 10:23 am, in reply to "Auto advance ADT unit "

I have a very good ATD going spare but it's for a Venom and (I believe) has a much finer pitch gear wheel than lesser marques.

Re: Auto advance ADT unit

Posted by Brickboy on March 8, 2025, 12:55 pm, in reply to "Re: Auto advance ADT unit "

Thanks Jimbo, but I think you're right, an Ajay would probably make it quite unwell!!

Actually Ajays have the inferior chain driven ATDs but thank you for offering

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