right Today head off fitted the canley supplied gasket , retorqued , tappet reset, timed, and she runs fine
compare old gasket and the canley gasket with the Payen from Rimmers and the problem is evident
the payen gasket Fire rings are half the width required to seal against the clamping load of the head
so this confirms the Triumph Payen Gasket is not fit for purpose , any purpose .
the pic shows the wildly differing half the width rings
there's a lesson for us all here
Pete