From your picture with the advance retard cable on the right IF the magneto turns clockwise then pulling the cable tight will move the cam ring anticlockwise which will advance the timing, slackening the cable will allow the camring to move back clockwise which will retard the timing.
If the magneto turns anticlockwise then a taut cable will move the camring anticlockwise which will retard the timing a slack cable will allow the camring to move clockwise which will advance the timing.
The rotation of the magneto as described above is seen by looking at the mag from the lefthand side of the bike.
The magneto on my Norton Big4 which has the advance retard on the same side as your drawing turns clockwise thus taut wire full advance slackwire full retard. When timing the bike it should always be done on full advance. Good Luck
