Boost bottle is a waste of time. All it will do is eventually crack your intake boots.
What broke off of the pistons? Top or skirt? If it was a piece of the top, hopefully it went out the exhaust. If it was the skirt, there might be some metal floating around in the bottom of the crankcase. You can try to flush it out, but watch for any damage that could have occurred. Might be a good idea to split the cases and find out why this happened to begin with.