Hi, just a curious question......lm having an issue with my daynamo, which I have to replace now.
The bike is a 1942 m20 with a sidecar.....
If I’m replacing to a 12 v magneto, and of course replacing all the bulbs.....and the battery, will it work?
Tnx
Rani
The magneto is incidental as it has nothing to do with the battery. But no problem if you want to fit a 12V dynamo-regulator-bulbs-horn-ammeter and battery.
I meant that I need a 12v battery as well.
I’m just finishing to rebuild the bike, and I’m wondering why not to turn it to a 12v.
If I have to deal with the magneto anyway.
When I was restoring my M20 last year I had to have the dynamo rebuilt and could not think of a reason to stay with 6v. I had it rebuilt 12v to give a wide range of lighting options, allow easy sat nav, phone and other charging.
You can use the dynamo as a 6V one and just ask more of it with a 12V regulator you can get a very robust one from Dynamo Regulators ltd that you can run as either 6 or 12V what you find is that you can get 12v field coils and armature but then you only have limited options as to regulators, so it’s easier to leave it as a 6v and just ask more of it
Will this still work using the period short dynamo which i think are 40W,. I know the longer 60W dynamo can be used for 12V without alteration and just using a 12V regulator. I would have thought the short dynamo would have to work hard to work a 12V system. Tim W
If you do convert it's worth considering also switching to -ve earth.
This will give you more options for using LED lighting if you wish - particularly the headlight bulbs which are difficult to use with +ve earth due to the internal wiring of the bulbs.
Dynamo Regulators Ltd as mentioned by Dave sell a wide range of LED bulbs which are polarity free so can be used on both pos and neg systems.
REgards, Mark
Remember you don't get anything for nothing...The dynamo needs to run faster to produce 12 volts than it does at 6 volts so it won't produce full output at the usual revs...
Also you will still need to run a headlamp bulb of a sensible wattage...I used a 35watt halogen bulb on my civvy M21 when running a 12 volt set up and found that to be effective...Ian
So as my previous post can i do this with a short 6V smaller output dynamo as original WD. Neg or Positive earth, even though all my pre war bikes are neg earth. I know fitting LED filament bulbs use less watts. So will my short 6V dyno cope with this without stressing it too much. I recon it will be near flat out all the time unless i do not much after dark riding.
I've always used the 60 watt dynamo for 12 volt use as I was advised the short dynamo wasn't up to it...Saying that I didn't try one to prove or disprove that advice...
An early 'long' dynamo that has a Bakelite end cover fitted, along with an earlier type of brush cover band would be reasonably discreet I would have thought...Ian
