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Magneto Questions

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Evening Guys, 
Carb now rebuilt so looking at the Magneto. I removed the cover and the copper band is only connected on the one side the side inside the circle is Separate. Is this correct? Does it just push against it? I take it the wire for the stop goes into this cap. 

The inside looks grubby should I strip it down for a clean? 

Thanks 
Craig

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The moving point and its pivot are probably so worn that the timing goes crazy above 3,000 rpm.

Strobe it and see.

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The biggest issue with magnetos is ingress of oil. Your magneto looks to be free of oil.   
From your photos, the first job would be simply to remove the points and polish off the corrosion products. Then recheck the quality of the spark.

Get a proper Lucas manual for the magneto to study before you decide to dismantle it.

To answer your first question, yes the earthing strap is held in between the brass strap at both ends and the carbon brush is held against the head of the bolt holding on the points 

The cable from the handle bar cut out switch then screws into the cover exactly the same way as the spark plug high tension leads 

 

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Looks  like it needs a clean up.  The points and springs look like they were set well initially.... a long time ago.  The build up on the periphery of the points is evenly spread and there is no spanner rash on the various fixings.

Clean up the contact surfaces with fibre strips, test for continuity across the contacts (almost zero ohms), then give it a spin with a plug grounded to the body and see what you get.  If there is no spark, you probably need to go deeper.  If it does, strip it, clean it and set it up with new contacts and a little lubrication then see what you get.

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Craig,
magnetos are like the little girl with the little curl. When they are good they are very very good but when they are bad they are HORRID!

If your mag has been rebuilt since say year 2000 and the armeture was sealed with epoxy, you may get away with a good clean.

If it were mine, I'd send it straight to an expert for a full rebuild, Inc rewind, condenser, pick ups and insulators on the bearings. 
Don't even pull it apart, chances are you will break the slip ring maybe even the earth brush.

A bloke in South Australia did mine two years ago for $600 AUD. (about 200 UKP )

A good idea is to get a 'Bright Spark' condenser. Or even get Bright Spark to do the whole job.
Their website is very good.
Don Anson Melbourne 

Jonathan,  3 dollars to the pound is not the rate the Bank of England will pay, but it is close to it whenever I buy anything from The Old Dart, which includes postage of course. 

It's the cross us Colonials have to bear if we want to ride old bikes.

And Al, I'm still waiting for the girl with the curl, but I've met plenty that we're horrid.☹️

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As far as I'm aware it has not been apart. When my uncle started working on the bike around 20 yr's ago after it being in the garage from 1965 he seemed to concentrate on wheels frame and tank. 

The Carb was a complete mess so I expected nothing less from the magneto. When I say clean it I take it I can remove the centre bolt and remove the contacts and there is a keyway on the back so I do not loose the timing? 

Sorry for the basic questions but this is all very new to me. I have downloaded the Lucas book and will have a read over.

https://library.brightsparkmagnetos.com/library/LWImags/Motor%20cycle%20magnetos%20N1,%20KN1,%20K1F,%20K2F,%20KVF,%20Sec%20L-5,%20Pt%20A.pdf

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Yes there's a small tab on the points to fit into the armature so the points go back in the same alignment from where they were removed 

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That's another thing I need to consider a strobe light (Not used one of those since the 80's building X/Flow engines).

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To use a strobe you will need to accurately determine top dead centre and remove chain case  to mark out the alternator rotor and stator. 

 



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