The ignition curve on a 4 stroke is very different than that of a 2 stroke. A 4 stroke will either continue to advance as RPMs climb, or at least top out and stay there. A 2 stroke ignition curve retards after the RPM the pipe was tuned for. By backing off the advance, it raises exhaust gas temperature. The speed of sound varies with temperature. Higher temps makes the sound waves in the pipe travel faster which then makes the pipe tuned for a higher RPM. So the ignition curve is retarded at high RPM to broaden the usable power range of the engine. Now assuming the base advance is the same, it would likely not damage your engine not retarding at high RPM, you would simply lose top end power as the pulse wave in the pipe hits the exhaust port after it has already closed. Now let's get back to that assumption. You cannot technically advance the timing in an electronic ignition. That would be like predicting the future. The pulse trigger is what is advanced. The CDI has to delay the actual spark a certain amount of time after the trigger to get the right timing. Less of a delay now means advancing the timing from where it was previously. I would not assume that the advance position of the pulse trigger is the same between any 2 machines let alone between a 2 stroke and a 4 stroke. Therefore, your base advance may be way off and that could result in engine damage. You can do what you want, but make sure you are willing to accept the consequences of the assumptions being made.
