Originally Posted by Elgavilan
Then how are you going to line up the timing marks?
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Make new timing marks to coordinate with the new hole pattern. A #2 carbide center drill does an excellent job of engraving. With a CNC milling machine you would locate the sprocket center, index the original timing marks, determine the number of sprocket teeth required for an adequate margin between the bolt holes and then rotate the hole pattern and the markings. The sprocket has 32 teeth which is a 11.25º separation angle.
It's doubtful that 11.25º would provide an adequate margin between the holes so I'll use two sprocket teeth or 22.5º for the example. For a 2º incremental advance you would rotate the hole pattern and marking 20.5º clockwise, 18.5º clockwise, 16.5º and so on. For a 2º incremental retard you would substitute counter clockwise for clockwise in the example.