Speedfight 50 break in prcedure

I blew the engine on my speedfight so I am going to rebuild it later today.
The garage I took it to said i only need a piston kit and small end bearing but i would get away with the original barrel.
When I put the new piston in how should I go about breaking the rings in etc?

 

Let it tick over and warm up for about ten minutes and that should allow the rings to start to bed in. Do you know what caused the engine to blow in the first place and has the fault been cured, otherwise it will happen again.