Gearbox "Shunt"

[limax2]

Aha it might be the sprocket then, I recently changed the sprocket nut for the larger one.

I will double check the free play at the sprocket side, if yours is moving that much then thats where my slop is coming from.

Ill have a look tonight.

I think Fazerider is referring to the free play inside the gearbox rather than the fit of the sprocket itself, so nothing to do with the sprocket nut. (Unless it's come off!). A certain amount of free play, measured at the sprocket as mentioned, is normal. It is due to normal clearances in the gear drive train but mainly in the gear drive dogs in the mating slots.
Reducing the clunk is a lot to do with general feel for the throttle responce and a slack cable etc. will make that more difficult. (Not to mention tapping out the music in your ears  ).