The easiest check for sprocket alignment is to look at the clean shiny patch on the chain rollers. If the clean area is all to one side and not centered, the chain is being pulled on out of alignment. The munge on the rollers should be about equal on both edges up against the link plates. If the noise has been going on since you changed sprockets, my guess would be the chain is really tight. Is your new sprocket bigger than the one it replaces? Even 1 or 2 teeth will drastically change where the rear wheel needs to be in the swingarm for proper chain slack.yeah buddys dont seem to care too much as its not their bike...!
might just be an alignment... though im sure the rubber on the front sprocket quietens things down a bit