Deburring your engine parts is a good practice. Square edges promote pre-detonation, which isn't a good thing. In order to get the compression that's desired, you can use a porting tool to match the shape of the piston pocket with the valve. You can take a fine emory cloth at home to deburr the sharp edges on your engine internals. Please note that this is an advanced level technical tip. Listen below as John "Bundy" Mitchell explains the art of deburring a piston.