Changing Sprockets KZ550 1982

Hi all,
I am having some kind of "clicking" noise whenever I am riding (the faster I go, so do the clicks). I have narrowed the sound down to at least the rear sprocket (an/or the chain itself)... My question is, when I change the rear sprocket, is it a must that I change the chain and the front sprocket at well? Could really use some guidance on this one guys, thanks.

When replacing sprockets, do both of them(engine,or countershaft sprocket) & rear sprocket and chain.

Old parts will quickly wear out new parts.