'59 G12 ignition

Information relating to the Matchless G12 or AJS Model 31 650cc twin
SPRIDDLER
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Re: '59 G12 ignition

Post by SPRIDDLER »

I served my apprenticeship (in the 60's) at a RR, Bentley and Jaguar main dealer and would love to work on a Griffon or Merlin engine. Have often stood for ages ogling them in museums.

I'm a frequent customer at my village post office and the lovely lady behind the counter takes my parcel and with a knowing look (at this sad old boy?) and with a roll of the eyes says "More priceless old bike parts?"
How we laugh.
'There is a tide in the affairs of men
Which taken at the flood............'
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ajscomboman
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Re: '59 G12 ignition

Post by ajscomboman »

Having just purchased a Thorspark electronic unit to fit onto a dead G15 I've been following this thread with interest. Until yesterday the Thorspark was operating perfectly and the bike fired with relative ease and would idle nicely straight from cold. Not having run it up for a couple of days I went out and tickled the carbs turned on the ignition and it fired once, pre ignition I suppose. Thinking nothing of it I tried to kickstart the bike and bugger all happened. Tested all the obvious components that you can do with electronic and have come to the conclusion the trigger unit or hall sensor has decided to die. The reason for fitting the Thorspark was that I didn't want to open up the Norton motor and as the mag appeared to be dead this was the simplest solution. Now that it's died I decided to remove the mag and check everything over whilst the Thorspark is away being checked. Out of curiosity with the mag off I went to town cleaning it all off inside and out and decided to install the points again, buggered if it didn't spark straight away when being turned slowly with a battery drill. I think I'll reinstall it and run it till it dies and keep the Thorspark on the bench to use if it dies. :headbang: :headbang:

Only good thing that's come out of the whole episode is by removing the mag I've found that the timing chains are buggered and need replacing at the same time. Being lazy in the first place and having it backfire has at least saved me having grief from the worn chains at a later date. :beer:
Groily
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Re: '59 G12 ignition

Post by Groily »

Gawd - you'll probably need one of those timing chain jig tools now Rob, to hold the shafts in place while you sort out the cam chain tension.
I didn't know I needed one until someone of the Norton persuasion insisted I absolutely did, so I got one.
(Altogether too much chain for my taste in them thar things. AND the top end is as big a PITA as a Beesa twin's to stuff together. I long believed there was just nothing more painful than a pre-unit Beesa, but hmmm, not sure any more - Spoilt, see, by the beautiful simplicity of the AMC twin top end!)
With any luck the mag will work a treat now anyway . . . I thought these modern gizmos were foolproof? (Actually, No I darn well didn't.)
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ajscomboman
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Re: '59 G12 ignition

Post by ajscomboman »

Bill what I need is a long lie down! The whole saga of fitting electronic ignition was to avoid delving into the chain nightmare! :headbang:
I was being lazy as I'd heard about all the nightmare issues with the chains and having to remove crank and cam nuts which can be a bit off a bugger! Anyway now the Thorspark has gone tits up I'm right where I didn't want to be and a whole lot poorer. It grates even more now that the bloody mag has sprung back into life despite the earlier efforts of trying to revive it whilst it was in the bike. :headbang:
Anyway when you have time enlighten me more about this jig and any tips by e-mail. All the best Rob
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Re: '59 G12 ignition

Post by G15 Roy »

When you wake up give me a call best to sell it cheap to someone that can get it sorted ;)
Roy
Groily
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Re: '59 G12 ignition

Post by Groily »

PM'd you Rob. Cheers, Bill
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