Inital thought was exhaust leaking too.
Is it possible you have an exhaust leak close to the head? The sound will get sharper as you get closer to the engine and could sound like engine rattle. I use shredded facial tissue on a clothing hanger to look for leaks in tight places. Best of luck to you.
Cheers!
It was a rattly clutch basket :exclamation but no leaks:nana
PMSL ha ha!Please tell me you don't mean skin !!!!