Magneto

[Kevin N Bayliss]

My Magneto fails to spark after sitting in a garage for 30 odd years, no surprise here.
I have dismantled the mag and have found the bobbin has an open circuit, easy fix the bobbin requires to be rewound.
While doing some internet research I came across a company called Brightsparkmagnetos dot com.
They have a device which replaces the buried condenser in the armature and places it in the end along with the points.
Very cheap and easy to replace if it goes wrong, you could easily carry a spare along with a couple of spare plugs.
I am going to give it a go and will update when mag is rebuilt, in the meantime has anyone else used something similar.
Kev

[chris wastell]

i ve seen these advertised, looks like a great idea.

[Tman]

I had one an Empire Star. It worked fine in the time I had it, but I only ever considered it to be a short-term fix, and no real substitute for a mag overhaul and rewind.
I believe you still need to open up the mag and disconnect the existing capacitor in the armature (if it’s merely failing rather than O/C) as the Brightspark replacement won’t work at it’s optimum if it’s still got the old cap paralleled up to it.

[BRIAN MARSHALL]

And.. if you pull the mag to pieces you can easily lose the magnetism from the magnets unless ‘keepers’ are applied.

[Kevin N Bayliss]

Yes you are both correct, the original condenser needs to be disconnected for the Easycap to be at its most optimum, but the Easycap is not a short cut to get a mag working, the magnetism and bobbin have to be in good or refurbished condition, it is just repositioning the condenser for easy access in the future in case of failure it can be replaced without sending the mag to be reconditioned. Yes you need keepers to keep the magnets from losing magnetism, I was forgetting someone might just try to do this without the correct info, I’m waiting for the bobbin to be rewound and will then be able to rebuild my mag and test it. Time will tell if it’s a good move or not. Kev

[Kevin N Bayliss]

Now had chance to get the bobbin rewound and tonight refitted to the armature and rebuilt the mag. Fitted the easycap as per instructions (2 mins) and tried it, wow what a spark, hardly turning over and a good spark from both leads.
all bearings are good, but are not expensive to replace anyway

so bobbin rewound approx £110 seems to be average price
Easycap £13
slipring £21

a bit of work, but I should have a good mag for many years.
Kev

[efr215]

Sadly magneto repairs are rather more involved than might first appear, I came across a contributor, user name “magnetoman”, on the Vincent Owner’s Club website who is well worth a read. This chap knows magnetos and what is more has done a good deal of testing and research to back up what he says, he also presents his case in a clear and readable style.

Here is a link provided on the VOC website:

https://www.britbike.com/forums/ubbthreads.php?ubb=showflat&Number=446733#Post446733

[Kevin N Bayliss]

Agreed, you cannot just rush in without knowledge otherwise untold damage could occur. You can get some interesting comments and suggestions or websites as you suggest which make interesting reading even if you do not intend repairing such yourself. Some people will not be interested in this topic and others will be.

Anyway My Scott is now closer to being used and over time I will endeavour to pick up this and that to put her back to original, but I’m not waiting for the pleasure of riding her.

Heres a quick run after trying the mag.

[Tman]

Kevin, it seems strange that you didn’t have the capacitor replaced while the mag was being rewound? Normally the two procedures go hand-in-hand, so was there a reason why not?

[Kevin N Bayliss]

Simply, yes, Normally the capacitor is one reason for mags being intermittent or failing or weak spark and having gone to the trouble of rewinding the bobbin (due in this case of failing ht coil) I wanted to give the Easycap a go so in future IF the condenser does fail it is a three minute job to replace and can be done at the side of the road. Ive kept the original condenser and removed the earth contact so I do not have to fit a nut in position to hold the circuit breaker plate in as with new embodied condensers, effectively just providing the original fixing. Is this the wrong way to go, only time will tell, but the spark at very low revs is superb. I will keep you updated with performance.
Also Bill at Brightspark emailed me with an answer to one of my questions about the parts they sell after finding out what I was doing and gave me the correct slipring part number for Scott clockwise rotation and I bought it, good job as the original that was fitted to my mag was not the correct one. Thanks Bill. Kev

[Tman]

Fair enough, though a modern capacitor fitted by a reputable rebuilder should (and apparently do) last many years. I have one of those Easycaps bought from Bill (in person, in France!) but to me it’s a standby device really.

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