Most motorcycle ignitions don't use hall effect - they use reluctors which is just a fancy name for electromagnet. Normally the pole is magnetised and when the flywheel or disc comes close the output will be a positive pulse and when it goes away, a negative pulse. On my RGV two stroke the flywheel 'lump' (actually one for each cylinder) is used for both timing and the amount of advance - the positive and negative pulses are both detected by the micro - the positve is the angle of most advance and the negative is the angle of least advance - if the micro fails the circuitry just gates thru the positive pulse. Most of the newer four strokes have discs with different widths so the micro can determine which plug to fire. An old permanent magnet stepper motor from a 5 1/4 inch disk drive makes a good reluctor simulator. Anyhooow, one normally uses a comparator to sense the reluctor - this gives you a nice square pulse to feed your micro. Also, if you want to play around with ignition timing - use a micro with a PCA in it like a 89C668 - apart from being in circuit flash, the PCA makes easy work of timing issues.

So , what are you wanting to achieve?