Ignition Timing Confirmation

[groily]

Got back a bit early today so nipped in the garage took a couple of photos gives you an idea of my setup.

That's pretty much how I do my Notrun engines, with the useful benefit of their end-feed orifice on the crank. Others I do with the timing disc on drive side if primary is off, otherwise, back to poke and prod down the plug 'ole.
Doesn't really matter that much I reckon, but if a mag's fitted, I'd always check both sides for unwanted variation (another can of worms altogether). An uneven firing interval is often worse than a small error on the advance setting.

[bikerbob]

Thanks for that tip musky will make one plenty of old plugs in the garage had a go at settting timing today getting the correct degrees each time no problem but each time I tighten the ATD unit the timing alters slightly will have another go Thursday have to go to a funeral tomorrow have you noticed the older you get the more fuerals you have to attend.

[Greybeard]

... have you noticed the older you get the more fuerals you have to attend.

Don't worry, that will stop one day 😜

[chaterlea25]

Hi Bob,
Make sure the magneto taper and pinion bore are absolutely free from oil
thread on the nut until it has a half turn or so to go, set the timing, put a suitable socket over the mag nut and give it a tap to seat the taper, then tighten the nut
If it still slips, rub a little chalk on the magneto shaft taper and repeat

John

[bikerbob]

Well I got the timing set correctly so I thought but the bike would still not start so out of curiosity I decided to try setting the timing on the other cylinder and that's when the problem showed up points just opening on the drive side cylinder but on the timing side cylinder the points gap was about 10 thou so obviosly a cam problem. Have contacted the guy I bought it off he was very apologetic could not understand it and has said he will correct it and refund my postage so magneto is now on it's way back to him. Such is life.

[groily]

This is a classic problem BB. Not always the camring, there be several possible causes. I scribbled about this a while back, and I think if you look here there may be relevant bits.
https://www.a7a10.net/forum/index.php?topic=16557.0
Don't know what Cheeserbeezer might be able add to improve/correct/amend, but there are several things to look at.
Probably the hardest thing to rectify on a K2 or V F frankly, and other remedies / causes need looking at before taking dremels or other grinding weapons to camrings, or spending literally a couple of hundred quid on new ring and / or housing. Dynamic testing across the rev range is - seriously - not a luxury; it's a necessity.
Tis why I keep banging on about 'check both sides' - you obviously have an error of multiple degrees on the mag, which will be doubled on the crank 'cos it goes x2 the speed.
Tis why I am happy to run a couple of bikes on fixed timing, having got their mags to deliver 180:180° sparks after a lot of sweat!
Tis also why 'strobes are good'.

[bikerbob]

Thanks for that groily have read that article but some of it goes over my 80 year old head Have had an email from the person I bought it off and ha say's he has sorted it out and retested the mag all OK. It is a fully refurbished mag everything is new only the outer casing is original it comes with a 3 year warranty and is now on it's way back to me and he has refunded me the postage and when I spoke to him on the phone  he was at a loss as to how he sent this mag out with that problem as he normally checks for this problem. He say's he has refirbished over 200 mags over years well we will wait and see when it arrives. Been away had a cup of tea and reread that article and now maybe I understand it better so these cam rings as well as the lobes not being of equal height thus giving you different points gap they may also not be at 180* so not sparking at the correct time..

[Colsbeeza]

Hi Bikerbob,
 I want to emphasise what John Chaterlea said. My magneto guru said that the shafts are fairly fragile and bend easily - he has found many needing straightening, so fitting the ATD without sideways force is important. John's method will ensure minimal forces on the shaft. I don't stuff around with them myself - just pays my dough and takes my chances. I do check the points open the same on both sides, and set the timing with indicator dial on cush drive and points opening light from The Magneto Guys, and I set the ignition to 31DegBTDC with ATD wedged to full advance. It does run sweetly.
Col

[BSA_54A10]

And to add even more to John's post
TAP means exactly that a tap
If you slog it then the taper will bounce off
I find a dead blow leather faced hammer ( mallet ) works best

[JulianS]

Showing how vulnerable the armature can be.

[orabanda]

It's good practice to use fine valve grinding paste to lap the pinion gear onto the magneto shaft.

Only takes a few minutes usually.
Richard

[trevinoz]

The armatures with the 15mm bearing seem to be a bit fragile but the 18mm version doesn't seem to give much grief.

[Colsbeeza]

Hi Trev,
When was the change from 15mm to 18mm bearings?
Col

[trevinoz]

Col, I think that the change was in the early 50s.
Chris Zoch reinforces the 15mm armatures when he gets them in for repair.
Trevor.

[Colsbeeza]

Thanks Trevor,
My spare is a 1956. Chris is working on it now.
Col