hey rob. u should always have the sprocket on the engine lubed up and also the clutch arm should have grease inside it.
When u say the nosie is a repedative clang that isnt clutch noise. to check if its the piston take ur spark plug out and see if the gap has been shortened!!.
other wise it might be the chain or sumthing on the bike just being hit.

wen u get some pics we will be able to know more.
Good luck and keep ridein.

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