Magneto control cable questions...

Information relating to the Matchless G80 or AJS Model 18 500cc Heavyweight.
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Magneto control cable questions...

Postby Pharisee » Sun Feb 02, 2020 1:32 pm

I intend to replace all the control cable on my G80CS but I have a question (or two) regarding the magneto advance cable. It's a Lucas "Competition" mag as you would expect.
If I order a new cable, will it come with the threaded aluminium 'adaptor' and spring already in place? I can't see any way of removing them without cutting the inner cable as the nipple at that end won't go through.
If it doesn't, is that 'flat nipple at the mag end the correct one or do I have a cable that somebody has made up?
Thanks
John

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Re: Magneto control cable questions...

Postby Rob Harknett » Sun Feb 02, 2020 2:18 pm

usually do inc rubber gromet.
Ashampoo_Snap_02 February 2020_14h15m55s_002_.jpg
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Re: Magneto control cable questions...

Postby Pharisee » Sun Feb 02, 2020 3:19 pm

Rob Harknett wrote:usually do inc rubber gromet.
Ashampoo_Snap_02 February 2020_14h15m55s_002_.jpg


Thank you, Rob... That's exactly what I wanted to know.
John

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Re: Magneto control cable questions...

Postby Pharisee » Tue Feb 11, 2020 2:13 pm

Right... I've fitted a cable. The last bike I rode with a manual advance/retard was probably my ol' Norton ES2 and that was a long time ago, but I seem to remember that the lever on the handlebars moved further than the one does on this G80CS.
I've measured a couple of things... The magneto cam ring is approximately 1.9"" O/D and it rotates approximately 0.25" at the circumference from full advance to full retard. Some simple arithmetic makes that approximately 15° of magneto rotation or 30° of crankshaft rotation.
I can't find any figures that tell me what full retard should be but from your collective knowledge and experience, does that sound about right?
Cheers
John

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Re: Magneto control cable questions...

Postby ajscomboman » Tue Feb 11, 2020 3:22 pm

Why is it important to find exactly where full retard is?

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Re: Magneto control cable questions...

Postby Pharisee » Tue Feb 11, 2020 4:11 pm

ajscomboman wrote:Why is it important to find exactly where full retard is?


In the great scheme of things, it isn't. It's just that I'd like to know that I've got enough 'retard' so that I don't break my leg trying to start the beast!!

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Re: Magneto control cable questions...

Postby ajscomboman » Tue Feb 11, 2020 6:21 pm

I wouldn't worry , retard it fully and just advance till it fires, my CS's like halfway ish!

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Re: Magneto control cable questions...

Postby Pharisee » Tue Feb 11, 2020 7:18 pm

What I was really questioning was the small movement of the lever from full advance (lever forward, cable slack) to full retard (lever back, cable tight). I just seemed to remember that there was more movement on my earlier bike with a manual advance.
The photos show the two extremes of movement.

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Re: Magneto control cable questions...

Postby ajscomboman » Tue Feb 11, 2020 7:56 pm

Ah I see, looks ok to me, mine are the same. If you leave loads of slack at the adjuster end then it'll go right back but if most of the slack is taken out then you get the amount of movement you have.

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