Originally Posted by 2door
Simply filing away material from the woodruff key is not the right way to change ignition timing. How are you confirming that the rotor (magnet) is not moving on the crankahaft. Simply tightening the nut will not keep it where you put it. If the key is now more narrow than the key way it's a good bet your timing is all over the place; advanced and or retarded. You said that the problems started after you worked on the woodruff key. That tells me something. Install a new key and try it. If the issues go away, you've found the problem.
I was starting to think the same thing, I'd heard of my friend doing this on his dirtbike, but it had a tapered shaft which would allow it to fasten securely...acts fuel starved mostly- but the greezy smoke makes me hesitant to give it more...?