Just notice a lot of kitted engines are painstakingly built up and broken in , only to end in an early demise so reported . Are you guys checking the ring end gaps ? It's possible that the rings are expanding, touching, bowing and either seizing in the bore or catching the port edges and snapping . A hotter running engine needs an additional thousandth or two depending on the cylinder / exhaust gas temp and overbore . Any thoughts on the subject??