Gearbox "Shunt"

[alexanderfitu]

To hopefully put your mind at rest you could see what a few other bikes feel like when on a centre stand and rocking the back wheel. (Best to ask permission first or you might get attacked  :o  ).
I know you said it didn't do it before the sprocket change, which is a bit worrying, but it is easy to kid yourself when you become super sensitive to a possible problem.
Good luck.

Yeah I will have a look with at my xj600 in the same situation. Its eniterely possible that its been there the whole time and im just noticing it now.