rossco

Hi there. I recently pulled my sherco apart as there was a sharp knocking from the top of the cylinder which i am led to believe is piston slap. After rebuilding the bike with a new piston, rod, bearings, gaskets and seals, the noise is still present. I have now removed the cylinder to find 2 deep scores on the cylinder wall and i also find there is movement in the piston where there shouldnt be! If anybody knows of piston liners or other remedies, any information or help would be much appreciated.