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About Magneto and Dynamo

Discussion in 'Other Norton Motorcycles' started by pierodn, Mar 5, 2017.

  1. Rohan

    Rohan

    Joined:
    Aug 26, 2010
    All Nortons were 6v until somewhere in the mid 1960s,
    so all generator Nortons were 6 volt - as they left the factory.
    However, its the REGULATOR which really determines if its 6v or 12v.

    The original fitment black Lucas thingy would have been 6v,
    and set up as positive earth for the later 1950s.
    As the Parts Book and Owners Manuals would spell out.
    Cheers.
     
  2. Bernhard

    Bernhard

    Joined:
    Apr 20, 2011
    I understand that the 99 engine had a mag under the carbs and the dynamo at the front of the engine; it was not a combined mag/dynamo as the last pic shows;

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  3. Rohan

    Rohan

    Joined:
    Aug 26, 2010
    So why include it here ???

    Thats as the Nortons singles were though, along with singles from BSA Triumph Raleigh Excelsior HRD and just about every other bike make you can think of - except AMC.
     
  4. pierodn

    pierodn

    Joined:
    Nov 10, 2012
    Hi.
    It means i must use a 6V battery?.
    Whar Regulator i need for 6 or 12v?
    Thanks.
    Piero
     
  5. Triton Thrasher

    Triton Thrasher

    Joined:
    Feb 10, 2009
  6. pierodn

    pierodn

    Joined:
    Nov 10, 2012
    Hi.
    Thank you for letting me know better.
    Piero
     
  7. Rohan

    Rohan

    Joined:
    Aug 26, 2010
    Watch that the wire in older generators may not like being run at 12v, if you try and draw a lot of amps out of it.

    The generator generally needs to be rewound with a slightly heavier wire if you intend to do a lot of night riding at 12v. Can't say that I have tried it (yet), but this is the advice I was given, from the guy that does the rewinding...
    You can get halogen 6v bulbs these days too, so the requirement to go 12v has largely vanished ?
     
  8. Triton Thrasher

    Triton Thrasher

    Joined:
    Feb 10, 2009
    Using a 12V headlight of more than 60W would be optimistic, especially on the shorter 45W 6V dynamo. Not least because it will drain the battery pretty fast at low rpm.

    The 12V rewinds to 6V dynamos that I had some dealings with, had more turns of thinner wire than the original. After all, every schoolboy knows that 12V requires less current for the same power, than 6V. Unfortunately, the thinner wire is more delicate under old bike vibratory conditions and the rewound dynamos frequently fail.

    6V 35W halogen is a bit dim. 6V 60W (if such a bulb exists) would probably draw too much current for the dynamo, wiring and switchgear.

    An ordinary 6V dynamo regulated to 12V can power a 60W halogen headlight and I find that to be good enough for night riding. The disadvantage of this setup is lack of charging at low rpm (practically no charging at under 2,000 rpm). The battery soon goes flat and the lights go out if you try to ride through a town with the headlight on. Common practice is to use a pilot light of about 10W in town. I think trying to power electronic ignition with a Lucas dynamo will end in tears.
     
  9. Rohan

    Rohan

    Joined:
    Aug 26, 2010
    No-one even mentioned headlamps "of more than 60w".

    But a halogen 60w headlamp + leccy ignition already draws more than the 60w total those gennies were designed for, at 6v. Yes, jumping to 12v DOUBLES the potential wattage - but you'd have to keep the revs up to see that.

    Thats an interesting comment. I'll get back to you on that, but heavier wire is definitely required if you are going to (try to) pull 120w out of an originally 60w gennie, they apparently run quite warm if you are using all of that.
     
  10. dynodave

    dynodave

    Joined:
    May 28, 2003
    Re: Dynamo/generator design

    One of the large advantages of an alternator is that the brute output energy is created in the stator which is normally directly connected to the diodes. The tiny excitation current is what runs through the brushes. This makes for a better design than the dynamo/generator whose power limitation is that the brute power must exit through the commutator/brushes. While the armature wire might make the power the commutator wire connections get to hot and it will shed the solder. The regulators job is to save the commutator. Either 6v or 12v the total power through the commutator is the limiting factor and size of the wire or 6-12 or any other voltage is much less important.
    ????
    For the nit picker who may not know much about the 99% of alternators use a variable DC low powered rotor coil rather than stone age magnet excitation.
    That does not affect the power side of the alternator.
    It is too easy for others to understand the focus of the main discussion which is the SOURCE and routing of the POWER generated.
     
  11. Rohan

    Rohan

    Joined:
    Aug 26, 2010
    Re: Dynamo/generator design

    ???
    British motorcycle alternators don't have brushes !! - to use your best trump style.

    This information would seem to be well less than half, this time ?? !!
     
  12. Triton Thrasher

    Triton Thrasher

    Joined:
    Feb 10, 2009
    I did, as an illustration of likely maximum practical headlamp wattage.

    Once again, don't try to power electronic ignition with a Lucas bike dynamo regulated to 12V.

    Those flimsy gennies were hardly designed at all. What matters is how you can use them on a bike that you ride.


    It increases the power, but "DOUBLES" is not likely to work well in practice


    There is more power available at normal running rpm. A disadvantage is that at 12V, the 6V dynamo does not begin charging until a higher (double, in theory) rpm than when it's regulated to 6V. I find that higher rpm to be about 2,200 rpm. Others claim lower.



    What optimist said they were going to "pull" 120W out of a 6v dynamo?


    Why don't get yourself a bike and try these things, then report back with some interesting experience? Might even be helpful to the OP.
     
  13. Rohan

    Rohan

    Joined:
    Aug 26, 2010
    I've got no shortage of bikes !
    And just had a genny rebuilt to suit a Model 7, stock at 6v natchelly.
    With a LED bulb planned to try on it, along with the stock 35/35 6v bulb.
    [​IMG]

    I was comparing notes with someone just recently, and we both commented we've never ridden most of our old bikes at night - ever. The local club organised some night rides, so folks could actually try them at night, but the days/times weren't very convenient ( at the time I was working evening shift). Apparently a few folks found their electrical system wasn't quite as robust as they thought.
    The guy with the Velo with the Alton and the Cibie Halogen had excellent lights - and has done many 000's of miles with it..

    BTW, the reason the gennies run at 12v need heavier wire is so that the wiring doesn't run hot,
    and not heat the whole genny up, and keep the risk of melting the solder to a minimum...

    Speaking of 3 phase field excited alternators (with brushes), I have fond memories of spraying wd40 into a squeaky alternator on my bike (non British, obviously), and then noticing the light getting progressively dimmer as it got back closer to home. Just made it home on the pilot light.
    WD40 and alternator brushes would seem to be not compatible, a light filing is what is required....
     
  14. Triton Thrasher

    Triton Thrasher

    Joined:
    Feb 10, 2009
    I use an Alton and it works better than the dynamo.

    Unfortunately, I've had failure of two regulators and one generator supplied by Alton, So I'd hesitate to go so far as to recommend it.
     
  15. Bernhard

    Bernhard

    Joined:
    Apr 20, 2011
    WD40 was NEVER an electrical contact cleaner, I used a Cibie on my 6v bike which gave a bright light, but like others who have explained a 60 w bulb in a 60w dynamo meant the head light kept getting dimmer and dimmer, one solution is to have a separate fog light mounted above the headlight with a 60w light bulb for dark roads and reverse switch to a 35 w headlight around town or when going a low revs.
     
  16. Rohan

    Rohan

    Joined:
    Aug 26, 2010
    You don't need to be an electrical genius to figure that one out !!!
    (Can you get 6v 60w bulbs ??)

    Thats why folks used to go to the 12v conversion of these gennies.
    Since you can pull (nearly) the same amps out of them at 12v as at 6v,
    they then give nearly 100w - although as mentioned they will run warm.

    WD40 is actually quite good on electrical components. And says so on the can.
    It was its lubricating qualities on the carbon brushes that caused problems though,
    and their worn shape then meant there was no electrical connection...
    But the squeak did go away !
     
  17. Bernhard

    Bernhard

    Joined:
    Apr 20, 2011
  18. pierodn

    pierodn

    Joined:
    Nov 10, 2012
    Hi.
    Please, can you send me again the list of dynamo.
    Picture doesnt open any more.
    Thank you.
    Piero
     

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