AN sells something called an "IGNITION TIMING PLATE CHECK TOOL" part # 13.1769

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In the past on the spanners where TDC indicators/markings were debatable (i will say specifically on CI engines) ... the way this was done was to approach TDC and fill the bore with paraffin gently turn over the crank and rock it to & fro over TDC topping up liquid where necessary. The level of accuracy achieved was extremely high.
 
I know it is totally irrelevant to the original post and this timing disc but anyway my fixation on checking timing came from timing twin magnetos. Specifically the difference between cylinders using a K2F or even Jo Hunt MAG.

I ruined two sets of pistons before it dawned on my inexperienced self that because of cam errors and a misaligned shaft the timing differed between cylinders by more than 10 crankshaft degrees.

Melted the top of two pistons trying to cure it with carb main jets.

Very very silly
 
I have to chip in about this ignition timing check plate. In a post a while ago the problem I had was not just a badly positioned degree plate in the primary cover but a double marked plate which was ridiculous. How something like that even passed manufacture, never mind we live with that.
The AN plate I sourced and a new degree scale to which using piston stop and degree wheel I then set about trying to set the 20, 30 and 40 degrees to position the plate. This turned out to be pigs dinner but it held despite sitting too high in the case.
The later delivered check plate was mounted and did not line up so I was no further than before.
The method explained by Torontonian and baz was used just to run the bike and I must say it ran beautifully.
Now I have a completely overhauled engine on the bench with a Boyer ignition standing on the workbench which is leaving me somewhat perplex at the moment and sometimes leads to deep muttering and cursing.
I will put gearbox and engine back in the frame then try to set up the boyer for the basic spark.
Any suggestions regarding this procedure or work over regarding the primary case would be welcome.
 
I know it is totally irrelevant to the original post and this timing disc but anyway my fixation on checking timing came from timing twin magnetos. Specifically the difference between cylinders using a K2F or even Jo Hunt MAG.

I ruined two sets of pistons before it dawned on my inexperienced self that because of cam errors and a misaligned shaft the timing differed between cylinders by more than 10 crankshaft degrees.

Melted the top of two pistons trying to cure it with carb main jets.

Very very silly

Interesring!

I said earlier that Dave Degens always said that being super precise was irrelevant (within a few degrees).

However, he was a stickler for ensuring the timing between each piston was cock on.

I guess we take it for granted these days as wasted spark EI can’t be anything other than perfectly matched, but it wasn’t always the case!
 
Maybe there is some irony in there is enough window in the primary cover viewing port to have started the 16 to 44 degree plate graduations at a marked TDC, AN elected to copy the original plate for some reason when they could have pioneered new ground.
Perhaps a case of can not see the wood for the tree's.

I found it easier to get rid of the factory plate as posted and do just that on the stator with the easily verified TDC mark included.
 
Interesring!

I said earlier that Dave Degens always said that being super precise was irrelevant (within a few degrees).

However, he was a stickler for ensuring the timing between each piston was cock on.

I guess we take it for granted these days as wasted spark EI can’t be anything other than perfectly matched, but it wasn’t always the case!
Yes. Electronic ignition has eliminated this problem but any time you use a twin cylinder magneto of any make it is essential to checked the timing is the same both sides. Up to say 3 degrees you can split the difference but much more than that you risk melting a piston.

Especially in race or continuous high speed road use.

In my experience a difference is the norm rather than the exception. Even in so called reconditioned mags. A mag is an electrical and mechanical device.

Many repairers fix the electrical but not the mechanical.
 
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