Is your ring set using a total Seal gapless 2nd ring? If not set the 2nd ring gap at or close to .024 to help the top ring stay seated at high RPM and not chatter or become unseated( I can't think of the proper word for that phenomom of the ring not staying seated against the walls and the piston ring lands ) It is now recommended by most of the better ring companys and engine builders to make he 2nd ring a little looser(.001 per inch of bore size or so) than the top ring, IE top ring .004 per inch of bore and 2nd ring .005 per inch of bore