It may help if you say what engine you are referring to.
However I had a bike from 1970 and you could screw a special puller into the centre of the magneto and then screw a bolt down the centre of the puller. This would in effect hold the magneto and then push it off the shaft (probably held onto a taper and a woodruff key to locate).
So you may need a special puller with the correct thread.
Steve, April 2009
