My 1995 440 EXC shelled the wrist pin bearing up the sides of the cylinder, across the top of the piston and down into the bottom end. I do not know if it is even worth trying to rebuild. It has been impossible to locate a piston. Found a guy that will do the nikasil (spelling) for $175. Does anyone have any experience with this type of failure and or know where I can get a piston? Thank you in advance.