Take out the screws securing the magneto chain cover and remove the cover. Undo all the screws securing the timing cover to the crankcase. Three of these are inside the chain case and one of them cannot be screwed right out as it will be found to foul the chain. Loosen and take off the large nut from the magneto chain case support stud which supports the back of the case to the crankcase. Pull the timing cover forward off the large stud and away from the crankcase bringing with it the magneto, the magneto chain and the sprockets, and when it is sufficiently far away take out the screw which could not previously be taken away. Do not lose the small coupling which drives the oil pump.