ignition timing

[Duncan]

Alan, I think you might be overestimating my background knowledge, but please continue!

I should probably clarify that I am not advocating setting the timing wildly out just making fine adjustments with the lever position.

It is sound logic for the spark to occur at the optimal point but I am not sure if a small difference would be that noticeable during normal pottering about, providing the magneto is not too tired.

I have just had a look at my spare K2F magnetos the competition one has a small screw to limit the cam ring travel but the head is normal, the standard one however has what looks like a pressed in pin inserted from underneath is this the one with the eccentric head or have I misunderstood?

[Biscuit]

The small screw in the K2F magneto is in fact pressed in, the slotted head is just there to turn the eccentric stop end, this is how my K2F was, which is why I think this stop position is important.

Adopting the role of Devils Advocate, what about V twins?, one of them must be wrong (according to me!!) I recall reading in my Vincent literature many years ago that the spark on the rear cylinder was weaker than the front.

[Duncan]

A PR company would give a positive spin that with a V twin it was a design feature to prevent overheating of the rear cylinder.

Is it an issue with the pre war AJS & Matchless V’s or are they set up differently?

[GSAX1]

You are right Biscuit, about the rear cylinder on a Vincent. The magneto's flux is at it's peak every 180 degrees and when one cylinder is offset to this it's got to receive a weaker spark.

As a happy(?) Rapide owner many years ago I know this by own experience. When really hot the rear cylinder cut out at slow tickover speed, even with a reconditioned and remagnetized magneto. The beast was a real pig to start sometimes. My old Barbour suit is still salty from all the sweat it absorbed during hot weather days starting attempts .

MichaelEdited by - GSAX1 on 18 Feb 2007 12:36:06 PM