Smokey... I am pretty new to all this but with regards to break in, I did at least 5 or 6 tank-fulls of fuel without running flat out (I used 5% for running in)... Since reading a lot of the forum posts, I probably didn't run it in 100% properly but I have a feeling something else was at fault....

About 2 sessions ago, the plate that sits between the one-way bearing and the crank came a little loose... the tiny spring loaded pin that sits in the crank came out whilst the engine was running. At the time the damage looked minimal and the problem was fixed but im now wandering if this could have cracked the piston... hence the failure. As I already mentioned, I am new to this so probably missed the important signs of immenent failure...

Steve