Hi, just another question about magdyno ignitions.
(V)twin magnetos with a dynamo on top are hard (if not impossible) to find.
Has anyone ever tried to change a single magneto into a twin mag ? Is it possible and what does it take ?
Any thougts ?

Michael,

Yes it can be and has been done. But it requires another cam ring or cam faceplate as well as another slip ring. And of course you need another pick up. Make sure that the cam ring or cam face plate has the correct setting for your V twin (45 or 50 degrees).

Regards,
Leon

email (option): leonhop3@planet.nl

I believe Dave Lindsley in the UK makes the V twin cam rings...You can use the magdyno from a pre war Triumph or early post war Royal Enfield twin as a donor, so saving the job of machining the second pick up hole. I think I have a couple of NOS pre war pickups in my 'odds and ends'box..Ian..

email (option): ian@wright52.plus.com

Yes I've had one done, all as Leon said but I'm fairly sure the end casting (points end) also needed changing to go from face plate to cam ring type points set up.

Sidevalve 1000cc are 50° but OHV 500/750 are 45°

Yes it was Dave Lindsley who did my last one but its worth noting that when I picked it up he'd built it 50 degree & he took some convincing it should be 45° which was strange, but 45° is what I left with & it was a superb job, he mentioned a long wait on mag rebuilds when I spoke recently though.
Daves spares serice is extremely I find.

45 or 50 degrees, would that make a big diffence ?

No it wouldn't, the mag would work OK.
But the OHV VTwin is 45° & if I ask someone to build it correctly at 45 then I expect it done how I asked .. its not cheap!
Also in my case the mag end cover had also been stamped "50°" & I had to change that myself later.
We're talking about a bike with a value of over 20K, it justifies doing it correctly.
In my opinion, anyone with a vtwin mag will want good money for it & you are then faced with a complete refurbishment, better to get a suitable donor & have it converted

Josef Cingros a Czech guy is producing laser cut 45 degree cam rings and they are perfect.

I have both a G14 (50 degrees) and a J12 (45 degrees) v twin and I can tell you from experience that a 45 degrees V twin doesn't run properly with a 50 degrees camring: either the front cylinder is early and the rear one late or the rear one is very late. That will bugger up your engine pretty good.

@Ian: I would like those pre war pick ups if you have any left. Please send me a PM.

regards,
Leon

email (option): leonhop3@planet.nl

It was Dave Lindsley that said either mags could be used on either bike, he told me that while chatting in his workshop , 5° is only a 1.4% inaccuracy on the second cylinder. I wonder how many are that accurate on both cylinders when checked?
But your saying you have tried it ?
How can 1.4% inaccuracy make the rear cylinder "very late" ?
I can't see how 5° would be noticeable.

I think a 50 degree ring on a 45 degree engine would mean that the rear cilinder is 2,5 early and the other 2,5 late - if adjusted like that.
Right ?

It would be 2 1/2 degrees out each way if set up like that..but if you timed it correctly off one 'rise' on the cam wouldn't it be 5 degrees out on the other cylinder?.Life is definitely simpler with one cylinder.... ...Ian

email (option): ian@wright52.plus.com

Well I time mine as the book says on No.1 cam so the other one would be out.
I didn't want to start trouble with this, I run a correct 45 degree mag on mine, I wouldn't suggest otherwise.
However when Dave Lindsley done mine to 50° spec by mistake he said he will change it & did. He did say though that it would have ran OK, at the time I put that down to him making light of his mistake.
However after looking into it, it translate to No.2 cylinder firing arround 2mm different position BTDC than it should.

I just question how many are firing that accurately anyway, but also fully agree that having the WRONG cam ring is a very silly starting point for getting a nice running bike

Fred,

The rear cylinder gets hotter anyway and running it with a 50 degree cam ring certainly didn't improve that. It did run like you said and after the change I didn't notice much difference except for a cooler rear cylinder.

Regards,
Leon

email (option): leonhop3@planet.nl