I dont know what the timing should be on the kx60, but check that the flywheel has not moved on the crankshaft ( in rare cases the flywheel key can brake). The cdi often have a built in advance/retard function on most modern bikes, and I have seen cdi boxes lock in a full advanced or retarded state.
If you use a strobe light on the timing marks on the flywheel and stator, you should see that the marks align at some rpms and move away at other rpms. If you have the manual, it probably will list the timing advance in degrees at a certain rpm.