Did any of you Guys That had problems with Vertex pistons measure your Bore? They make an A, B, C, D, sizes or did you just get what they sent you? I have had the wrong size sent to me before.
I ran them in my 125 and 250 with no problems, as far as break in, let her rip after about 5 miniutes, never a problem. They ran them in the Pro Circuit bikes for years and I bet none of their top ends ever saw close to ten hours on them.