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Thread: Restoration of a Bosch ZEV magneto

  1. #1
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    Lightbulb Restoration of a Bosch ZEV magneto

    Some of you might be interested in the detailed description of the restoration of a magneto I posted to BritBike Forum under the name Magnetoman. It is the most extensive such description I am aware of on the web or in print, requiring 20 posts over four months to complete. The subject of the thread is a Bosch ZEV I restored for a friend's 1923 Harley-Davidson that he subsequently rode in the 2012 Cannonball Rally:

    http://www.britbike.com/forums/ubbth...46733#Post4467 33

    My obsession with magnetos was, ahem, sparked in the mid-1990s when I restored a BSA Gold Star that came with a nonfunctioning magneto. Rather than taking the time to figure out how to fix the magneto myself, I decided to send it to a specialist. That was a mistake. Although the specialist came highly recommended, had a very well equipped shop, and seemed quite sure of his abilities when I spoke with him, the magneto failed after 90 miles with what I recognized as a bad replacement condenser.

    Anyway, as a result of that unfortunate experience with a highly recommended magneto rebuilder, and as I wrote in the 'Epilog' to that thread, "Although I have no way of knowing for sure, I seriously doubt even the most heavily-equipped professional magneto rebuilder has the range of equipment and facilities I do for diagnosing and restoring magnetos." I should add that this is not an advertisement for restoring magnetos since I only do that for myself (and a few close friends who managed to corner me)
    Last edited by BoschZEV; 01-25-2013 at 11:49 AM.

  2. #2
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    I started buying Bosch ZEV magneto's in the early 90's also but i am in no way as good as you are.
    So how much did this job cost? Just to do the work I would say $1,000.
    I too send magneto's to the best guy around, and had a lot of problems with the mag and it cost some miles on the Canon Ball 2010.
    So you want to be the ZEV guy? I have a couple of doz. that need done? Most of the clean up work is done. Threads taped, screws cleaned up, and many other hours of works done to them.
    I use to buy them for $100, now there $500 and don't work. There are fake ones, cost $1,000.
    Thanks you for posting this, it is very good and i have learned a lot.
    Terry Marsh
    Last edited by marsh1915hd; 01-25-2013 at 08:17 PM.

  3. #3
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    Quote Originally Posted by marsh1915hd View Post
    So how much did this job cost? Just to do the work I would say $1,000.
    Well, I did it for a friend, so it was priceless. I didn't keep track of the time involved, but the work I had to do to make that magneto function as good as when new easily would have cost over $1000.

    Quote Originally Posted by marsh1915hd View Post
    I too send magneto's to the best guy around, and had a lot of problems with the mag and it cost some miles on the Canon Ball 2010.
    I have to wonder how you can call someone "the best guy around" when you say his magnetos failed you. If you had someone do mechanical work on your engine and it failed, I doubt if you would say that mechanic was "the best guy," so why do people -- not just you, but a lot of motorcyclists -- accept magnetos that fail? There is simply no reason a properly rebuilt magneto should fail.

    Quote Originally Posted by marsh1915hd View Post
    Thanks you for posting this, it is very good and i have learned a lot.
    Thanks very much for the nice comment.

  4. #4
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    The best guy around magneto was tested for three days just could not handle the heat. Condensers were all bad, it was not just my magnetos.
    By the time I have them cleaned up and working I have more in them than they will pay for one. No one wants to buy one for $1,200. They want a $500 one that cost $1,000 to repair. So I have not repaired anymore.

  5. #5
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    Quote Originally Posted by marsh1915hd View Post
    They want a $500 one that cost $1,000 to repair. So I have not repaired anymore.
    Yes, that's quite a problem. A magneto cannot be properly repaired for the $250 that people already think is too much. I would have lots of customers if I spent $1500 worth of my time rebuilding magnetos, as long as I only billed them $200 for the labor. However, if I billed what it actually costs, there would be very few customers lining up. So, I do what any rational person would do who has assembled a comprehensive set of instrumentation and facilities and actually knows how to diagnose and repair magnetos properly -- I repair them for free... (but only for a few friends ).

  6. #6
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    We have a lot of magnetos repaired for the shop. We do the dynamos and starters ourselves. But mags are an art. Other than some work with points, we send them out and are glad to have others who are experts. Last couple of years, I think we had about 40 mags done.

    Best guy we have found is Mark's Magneto Service in Ct. He has done some bike mags for me personally... but also a lot of Ghost, Phantom and Vintage Bentley mags. And these are for cars that are driven a lot. Not trailer queens.

    Mags run a LOT to restore right, especially if you have to rewind them. The prices of $1000 are not out of line. If lucky, they don't need rewinding.

    The main things to consider are a: A properly done job lasts for decades. b. You will pay for a properly done job. c. You will have to wait for a properly done job. d. If you get a cheap job, you may get it fast and cheap. You won't get it right.

    Buy once, cry once. The quality remains long after the price is forgotten. There is no free lunch. Choose your plattitude du Jour. But when it comes to Mags, find good people. Pay them well. Be nice to them. And you will get a mag that will outlast (probably) you. Cheap out and you'll just have to do it again. And pay for a flatbed.

    Cheers,

    Sirhr

  7. #7
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    PS... my mention of Mark was not to take away from Bosch ZEV... But to support his point that good work costs.

    We need more good Mag guys out there. And should be glad when anyone skilled in their repair comes across our radar!

    Thanks ZEV!

    Cheers,

    Sirhr

  8. #8
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    Quote Originally Posted by sirhrmechanic View Post
    PS... my mention of Mark was not to take away from Bosch ZEV... But to support his point that good work costs.
    I have no experience myself with him, but I do know he was the subject of much discussion during and after Cannonball 2010. However, I work on magnetos only out of interest (or, more accurately, obsession), and only for myself, so I'm not in competition with anyone who does it as a business.

  9. #9
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    These are intended for Lucas mags,I don't know if they could be adapted for Bosch.
    I'm all for doing a proper job on a repair,but if even good quality condensors are prone to give out in extreme heat,these would provide a roadside fix.

    http://www.brightsparkmagnetos.com/index.htm

  10. #10
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    Quote Originally Posted by Limey_Dave View Post
    These are intended for Lucas mags,I don't know if they could be adapted for Bosch.
    I'm all for doing a proper job on a repair,but if even good quality condensors are prone to give out in extreme heat,these would provide a roadside fix.
    Sorry, but I have to disagree. For the technical reasons I give in my thread on Britbike Forum, I definitely do not recommend using those condensers. Also, a proper replacement condenser would still be fine after crossiing the Arabian Penninsula in August. The rider will expire long before the condenser does. The condenser I recommend in that thread is rated by the manufacturer for full performance up to 85 oC, and then up to 105 oC at derated voltage. If the inside of your magneto is at 85 oC, your fuel tank is on fire. If your replacement condenser goes bad when it is warm, the rebuilder used the wrong replacement condenser.

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