I have a left hand mag on my M20 ("left hand" referring to where the advance/retard cable enters the mag).

When the lever is pushed away from the handlebars, the cable is slack and the ignition fully advanced. Pulling the cable tight (towards the handlebars) rotates the "inner bit" of the mag clockwise thereby retarding the ignition i.e. the position at which the points start to open.

My query is, on a right hand mag, when the lever is retarded by pushing the lever away from the handlebars, does the "inner bit" of the mag still rotate clockwise?

Sorry in advance as I do not know the technical name for the "inner bit".

I would presume that on both a left hand and right hand mag the points rotate clockwise.

email (option): sacombsashtrees@hotmail.com

Everything works the same in the mag, but the lever on the handlebars works in reverse. It's called slack wire advance or tight wire advance.

email (option): horror@blueyonder.co.uk

Thanks Horror.

email (option): sacombsashtrees@hotmail.com

Not always Pat. Norton's for instance have the same left hand cable as yours, but the points rotate anti clock, making it the normal tight wire advance.

As far as I'm aware??, the only manufacturer during WW2 to adopt the more sensible slack wire advance was Royal Enfield. Should your cable break, the cam plate would then automatically revert to the full advance position and allow you to continue your journey Ron

email (option): ronpier@talk21.com

Thanks too Ron.

email (option): sacombsashtrees@hotmail.com