Lucas MO1 twin magneto

Robert Watson

Well Known and Active Forum User
VOC Member
OK, I am planning on a couple of longer trips on the A twin this year and I have no spare Mag, I think that I should have one, even tho' the one on the bike is in great shape. Anyone got a rebuildable one sitting collecting dust. I think some early Ariels along with other make prewar twins used them. We can make a new cam ring and/or whatever else is needed, and have good rebuilder on hand.
Anyone?
 

Ken Targett

Active Forum User
Non-VOC Member
It's a clockwise MNV that you need, Robert. Similar to the MO1, but with V ring cam instead of single face cam, end housing to suit, and, of course, a segmented slip ring and two pick-ups. You might find an MN2 for a parallel twin more readily available than an MNV. You should be able to convert a clockwise MN2 merely by replacing the cam. Or you could convert an anti-clockwise MN2 by replacing the cam ring, CB assembly and slip ring.

Ken.
 

Marcus Bowden

VOC Hon. Overseas Representative
VOC Member
Robert I'll have a rummage around, using a mag/dyno unit some time ago testing on the lathe to see if I would damage the mag buy using the earth connection,, to incorporate a coil ignition system onto the mag points, it worked fine but reduced the mag spark by 2mm but it was jumping about 10mm at the time,,,again a lack of knowledge I was apprehensive that if the engine stopped with points closed and the feed through the coil ignition system !? Would there be damage to the magneto armature? I couldn't think of an easy way to make a centrifugal switch at the time (so it only connected when the engine ran) whats the answer please ,Bright-Spark, Magnetoman. Knowing younger brother is going to be in the same party with out me, I'd better make sure he has the appropriate spares.
 

Chris Launders

Well Known and Active Forum User
VOC Member
The MNV uses a different end plate and armature end to the MOI, the MOI armature has a segment cut out for the points, the MNV uses the keyway type the same as the K2F/KVF.
When I got my 11.50 Brough the mag was poor so I used an old MOI body and fitted a home made bearing cartridge and shaft to take HD ADV/RET and two sets of points, the MOI magnets affected the ADV/RET so I machined a bit out and glued a strip of lead flashing in, used two 6v coils and it worked brilliantly. Currently building a SS100 replica and have used a MOI with the windings removed, a single slipring wired through to the points, so I have power to the twin plug coil and condensor under the tank then down dummy HT leads to the mag pickups (which now have electric drill brushgear) through to the points with a KVF camring, giving me coil ignition with manual ADV/RET. If you want to convert a MOI I am sure there is an article on how to do this in one of the Brough maintainance books I have, I will look for it shortly.
Chris.
 

nkt267

Well Known and Active Forum User
VOC Member
I think a twin Lucas MSL(MS1?) would do if you can find one..I have seen a couple recently on Ebay.I have a single version on my 1932 Sunbeam, it looks loke an MO1 but has K2F type points and cam.John
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Chris Launders

Well Known and Active Forum User
VOC Member
Found out Brough article, it describes using both face cam and radial cam conversions.
You need to start with a mag with the right rotation otherwise it gets complicated.
Drill and tap body for 2nd pickup.
Fit twin slipring.
For radial cam type use KVF camring it will be 3 degrees out on one cylinder but should run ok ( balance the difference)
(if your mag turns the opposite way to the KVF you will have to grind new stop and adv/ret slots in the back of the camring to suit)
For face cam type you will need to grind down a section identical to the existing one but 156 1/2 degrees away (180-23 1/2(47 degrees divided by 2))
Cheap and relatively easy, especially if you can get a radial cam type.
OR get the bits and have it rebuilt proffesionally and then you know it's good.
Chris.
 

Robert Watson

Well Known and Active Forum User
VOC Member
Thanks for all the advice. My real issue is that it is not easy to find one in this part of the world, and I have looked on ebay several times and come up empty. If anyone has one or spots one that would be suitable I would appreciate a heads up

Thanks
 
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