I made some piston rings for an old British Villiers 2 stroke. The top end gap is 0.25mm second ring 0.30mm. Land gap 0.07mm and a back clearance of 0.175mm. I’m erring on the side of caution a little all round as I don’t have exact measurements from the (non existent) workshop manual and I’m not a competent machinist. They’re still much tighter than what came out of the engine. I spent many hours researching clearances - my scribbles at the end are about as good as you’ll get from me.
now I need to sort out the carby and fuel system
