Agreed, Jack, the lighter the piston assembly the better. I should have limited my comments to aftermarket piston assemblies available for the XS 650, all of which (JE, Venolia, Wiseco) are substantially heavier than stock; I'd post the weight comparisons for OE 75 mm./JE 77.5 mm./Venolia 77.5 mm., but the manual with my notes in it has gone missing. My comments were meant for the guys who are building for enhanced street performance on a budget, not the guys who know their stuff and are going all out with custom components--they'll balance the rod and piston assemblies and blueprint the crank as a matter of course!