SR1 magneto component purpose

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SR1 magneto component purpose

Postby asterysk_usa » Sun Nov 10, 2019 6:54 am

Image

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Can anyone tell me what is the purpose of the spring component that i have drawn a red line around.

I compared the internals of my SR1 with the Lucas diagram and this is extra


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1954 AJS 18S Cyprus export (frame decode says 1954 but many components match a 1955).

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Re: SR1 magneto component purpose

Postby Groily » Sun Nov 10, 2019 7:42 am

No idea I'm afraid. Doesn't seem to do anything or go anywhere much? Could it have somehow held a lubricating wick for the cam?

Looking at this pic, and also the end-on pic you posted in your other thread:

1. The HT coil looks a bit tired, where the brass tag emerges and also just generally. Worth putting a meter across from the brass tag to 'earth' to see what you get. 5-6000 ohms would be pretty typical for a Lucas-wound coil. If Open Line, not good. The rest of it looks OK though and I see someone has fitted a Brightspark capacitor - here's hoping the coil is OK then.
2. As Clive said, that one is from a stationary engine or something that isn't an AMC single. The drive end casting isn't quite the same as on the correct version. As the SR1 is pretty common, might be better to get one that conforms precisely to the beast, if you're wanting 'original' at the end of it?
3. The arrow is always indicative, but never definitive! It's easy to change the rotation - but chances are it hasn't been altered.

Have you tried to get a spark out of it?

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Re: SR1 magneto component purpose

Postby asterysk_usa » Sun Nov 10, 2019 9:11 am

Groily wrote:No idea I'm afraid. Doesn't seem to do anything or go anywhere much? Could it have somehow held a lubricating wick for the cam?

Looking at this pic, and also the end-on pic you posted in your other thread:

1. The HT coil looks a bit tired, where the brass tag emerges and also just generally. Worth putting a meter across from the brass tag to 'earth' to see what you get. 5-6000 ohms would be pretty typical for a Lucas-wound coil. If Open Line, not good. The rest of it looks OK though and I see someone has fitted a Brightspark capacitor - here's hoping the coil is OK then.
2. As Clive said, that one is from a stationary engine or something that isn't an AMC single. The drive end casting isn't quite the same as on the correct version. As the SR1 is pretty common, might be better to get one that conforms precisely to the beast, if you're wanting 'original' at the end of it?
3. The arrow is always indicative, but never definitive! It's easy to change the rotation - but chances are it hasn't been altered.

Have you tried to get a spark out of it?


It was refurbished by Brightspark in 2013 so that would explain the capacitor ! They fitted a new HT lead at the time and it did work but will test again shortly

Your suggestion of a lubricating wick makes sense, what lubricant would be best to apply to it ?
1954 AJS 18S Cyprus export (frame decode says 1954 but many components match a 1955).

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Re: SR1 magneto component purpose

Postby Groily » Sun Nov 10, 2019 1:48 pm

It would!
Done my late colleague Ken Targett, when the magneto was UK-resident presumably - so the coil will have been OK back then in 2013 and it will have worked to spec. Looks a trifle care-worn now though, although it may be fine still. If he knew what it was going on, rotation and cam-riming will be correct.
If a wick can be grafted on, I'd use a few drops of oil, or a smear of light grease, just enough to moisten the cam. Don't want slime flung over the points, obviously!

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Re: SR1 magneto component purpose

Postby asterysk_usa » Sun Nov 10, 2019 3:50 pm

Groily wrote: Done my late colleague Ken Targett, when the magneto was UK-resident presumably


Yes it was Ken who refurbished it. I sent it over by post and went to collect it personally, he showed me his magneto workshop setup which was amazing but the most impressive was his immaculate Black Shadow. He was such a nice person and a true gentleman, was so sad to hear of his passing
1954 AJS 18S Cyprus export (frame decode says 1954 but many components match a 1955).

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