if you lap the rotor and the key shears theres still a problem right ? ok ....now yamaha is supposedly switching the fly wheels (as read on another post)so if you lapped your rotor wouldn't that mean you've now changed the dimensions of the shaft? so the "NEW" flywheel yamaha is supposedly trying out would still have a bad taper due to the lapping since they are giving you a flywheel with the dimensions before the lapping !! i'm not sure exactly what part the lapping grinds down whether its the shaft or the rotor so maybe i am doing this post for nothing but this is just something that i took into consideration before i lapped the rotor.i am now the proud owner of 3 "SPARE" woodruff keys. that should hold me over till yamaha comes out with a fix for sure. i could be right or i could be way off target with this post but hey i'll never know if i don't post it right? i'd rather be safe than sorry !!