Not what I meant, just saying that shaving your piston rings is a good way to end up with a blown kit. Running your ped with a badly tuned carb is another way to do the same thing. So, to avoid both leave the rings nice and snug and just tune your carb well. The rings are not made of a very soft metal, they do not expand all that much unless you do something way wrong. If that happens the ring will expand in all directions and will likely get stuck in the ring groove. Im sure you have seen the pics of that. The little pin in the ring groove will stop the ring from going to far length wise and it will expand outwards causing a ... soft seize. Do it a bit worse and it will seize up permanent like.