need to get a new piston and rings and should just rebuild the top but you also need to see if it did any damage to cylinder walls the broken peice is still gonna be in there somewhere........i don,t want to alarm you but there just isn,t an easy fix that part iof the piston that broke has to be found cause it can cause chaos if just left in there, wait for a few more responses but i think engine is going to have to come out ...........................
