Electronic Ignition, Auto advance, and pinions.

[groily]

I guess I'm on both sides of this fence too, having bikes with mags (which I wouldn't ever change) and bikes which could have mags, but don't, as they have Boyer Bransden systems. But they also have upgraded alternators and modern regulator/rectifiers, which is to me a rather important consideration, and the largest possible 12v batteries just in case!
I've had limited trouble with mags generally over the years, barring one which failed in short order after a rebuild on my A which I mentuioned here a good while back. Like Brian, I have a boring tendency to re-do all new-to-me mags on site before they go outside this parish as my memsahib doesn't like hitching up a trailer. But even then there can be issues.
Without wishing to push anything improperly, for a bit of a discussion on capacitors and options, some folk might find a look at some of the analysis on a website I and a mate have been (still are) working on for a few months, at www.brightsparkmagnetos.com
What we've been trying to do, apart from invent a way of putting capacitors in a sensible place, is to get a good handle on what actually happens in a magneto. Because it's a heck of a lot more complicated than it sometimes appears!
I would slightly disagree about most restorers using the same capacitors, though, as I've got a dozen different ones on the bench from recently sorted mags from all over the place, as well as Lucas ones! The most commonly-used are probably Evox Rifa PME271 (or 261) series, rated 250Vac (they are mains suppressors really) but there are lots of others out there, often usd doubled-up in parallel. The all-important voltage ratings vary enormously, and resistance to fusing, capacitance and dielectric materials used vary considerably too. Capacitance varies routinely from 100nF to over 300nF, on the samples we have looked at. It's a bit anoraky, but some here may find it of interest!
Ah well, sun's out, time for a blast.

[bsa-bill]

had a quick deek at your site groily, look forward to reading more when time allows.
as my spare maggie is apart would be a good chance to try your thing out.

[groily]

I've sent you a PM Bill as don't want to sully the purity of the forum with 'trade' and get my much-rapped knuckles broken. But thought the link might be interesting in the context of this discussion. Cheers!

[chaterlea25]

Hi Groily,
On the subject of capacitors, have you come across the studies and testing done by Prof Charles Falco in the USA?
Charles is the head of the Physics department in University of Arizona and a BSA fan to boot
Quite often he comes to Ireland to ride in the Irish National Vintage Assembly
To cut a long story short !!
He recommends  fitting a pair of Panasonic 0.082 micro farad polypropylene film capacitors
pt number , ECQ-P4823JU
wired in parallel these will give 0.16 micro farad

Cheers
John O R

[groily]

Thanks John. I have heard of him but not had any contact so far. One to make a note of certainly.
Nor have we yet come aross a pair of those caps (or not marked as such). I do have a paired set of red polyprop caps I took out of a failed K2F on a Speed Twin for a mate here in France, they could have been similar but there were no markings. It is surprising how many caps have their markings rubbed off, possibly as folk try to protect their know-how! Some restorers just won't reveal what they use or sell caps to third parties, and it's a bore having to strip an armature to find out and measure the darn things!
We'll have a look at the panasonics on the www, thanks for the part number.
One thing I would say is that there is a lot of ime spent on discussions about nFs, but perhaps not enough on voltage ratings. LT voltage spikes can be surprisingly high. A lot of caps in use are primarily designed as mains suppressors so are rated '250Vac' or 275. Cheap as chips, and they serve well for what they are (mostly). While all nF ranges from 100 up to way over 300 work on a mag, as I now know having chopped and changed and modified one or other of my mule bikes umpteen times, inadequate voltage rating is a guaranteed failure over time, and often not very much time. As is inability to handle current, the old dv/dt thing.

Our primary object, however, has been to get the capacitor somewhere where we can get at it so we can treat it as a routine service item, just like with a rotating magnet instrument - or a Kettering ignition system for that matter. Because the simple fact is that no cap will last for ever on magneto duty, and it's a PITA to have to have a degree in archaeology to swap the things out!
Cheers and thanks again John.

PS just had a look on Digi-Key's site. None available, but rated 400Vdc and similar to look at to the things Independent Ignition Supplies sell in the UK, which I've used in the past. They're about 500vdc I think from memory. I dug similar to the panasonics out of a duff French magdyno in fact while trying to help a mate, as one of the French restorers uses something like. They do require careful potting though, as the wired ends are fragile in the environment we're discussing.

[chaterlea25]

Hi Groily,
I had a quick peep at your website, neat idea!!
If you send me a PM I can forward Prof Falco's article to you

Cheers
John O R

[Triton Thrasher]

Yes I was reluctant to go off magneto, but I have had two refurbished ( at he same place) both of them work adequately on my Flash but both are equally unreliable at starting the higher compression Rocket.
There must be thousands of Rockets out there that start just fine on Magneto, but mine wont (my mates won't either) and I blame the magneto rebuild, somehow it is good enough for a Flash but not anything higher compression, there is a good article in last months Real Classic by PUB re- magnetos which might have a bearing on this, to do with a/r units where by retarding the spark you actualy weaken it somewhat ( past max flux) you guys that are experts can explain this better than I can.

How did the Rocket start with a magneto, if you didn't retard the spark, or only retarded it a very little?

[bsa-bill]

It is a flash brought up to Rocket spec, retard was via a/r unit.
it now starts every time first /second kick, the only difference is the Pazon ignition.
Contrary to the impression given by other forum members I am not anti magneto, far from it, I intend to get the magneto tested to find out what is up with it, I would love to have the bike refitted with the magneto provided it would be as reliable as it should be.
I know it is difficult at times to get the intended meaning in a mail, but it would help if some members were a little less apt to jump to unfounded conclusions
(yeh ok I do it myself at times)

[GoldenFailure]

Hello all. Yesterday I fitted my magneto body replacement for electronic ignition, and the aluminium solid timing pinion from Lyfords as suggested by BSA Bill, but the gear stands proud of the next pinion when fitted, so only half the depth of the teeth are engaging. Initially I thought it was the gear, but now I'm wondering if it might be the Mag body replacement tapered shaft protruding further into the timing side case than the mag shaft did. Has anyone had similar problems who could make a suggestion? My only ideas so far are make a triangular spacer to move the whole body backwards, but then the locating flange will be lost making for imprecise gear meshing or to just ignore it, as its only spinning a metal wheel for the electronic ignition, not a heavier mag armature, and therefore needs less tooth contact?

All thoughts appreciated.

[bsa-bill]

Should look like this Goldenfailure, ends up about flush with the outside of the cam pinion.
Take no notice of the two holes in the pinion as these I added to make removal easier, although as you will have noticed there is an internal thread in the pinion to take a stud for removal. (it's metric)
 Do you have the pinion on the right way around I wonder ?

[muskrat]

 G'day GF,
              both of mine sit proud, both been on for quite a few years with no probs.
Cheers

[alanp]

Leave it. I've done over 1000 miles of mixed (!) riding with mine like yours and I checked it a week or so back and there wasn't any discernable wear to be seen. I recall it's on a taper and whenever tapers are involved things will be a bit variable in location since small'ish dimensional errors make large differences axially. It's kinda what you expect these days.

[GoldenFailure]

Hi

BSA Bill, yep, on the right way round (should I be insulted?! ) Interesting that yours fit correctly and Muskrats and alanps dont. Yes, I guessed the two extra holes were your idea for easier extraction, I was tempted to do that myself after seeing your picture, but laziness got the better of me!

Thanks Muskrat and alanp for putting my mind at ease, I wasn't relishing yet another technical problem!

Cheers

[muskrat]

 Got home from work early so thought I'd start up a few bikes. 4 out of 4 started first kick. 3 BSA's with Boyer and the XT with points. Life's good.
Cheers

[bsa-bill]

(should I be insulted?! Cheesy )

Yes I did think it was a bit silly when I mailed it, just I had to have a couple of looks at mine when it arrived .
Mine was quite a tight mesh with the cam pinion. also found the long magneto fixing nut was too thick to work so fiddled with an ordinary nut to get it on, slimming down the long nut definitely a job for another day.
added a couple of photos that might help