piston failure

[boosted22]

what would be the corse of this, the bike has been fine since we have owned it, then last race meet it slowed right down had no guts, when i got home decided to do a comp test showing up little under 120 psi, so stripped it down to find the piston had a small hole and crack down one side, just wondering peoples thoughts, we have had no trouble with this bike at all, has all ways went nice and hard, ive just rebuilt it, also when bleeding the water system does much come out from the top bleeder on the head does stright coolant come out or more bubbley coolant, does it come out fast or slow
thanks guys be stuffed with out this site lol

http://i1101.photobucket.com/albums/g424/boosted925/IMG_1752.jpg

[fomospede]

never seen that before
possibly not letting it warm up enough
or piston slap because it was out spec.

[mmsoup]

what fuel were you running?

[boosted22]

hey we ran the same fuel in three bikes and the other 2 are fine so dont think it was that. :)

[bloodswet&gears]

How much squish were you running? May have made contact with the head at high RPM.

[mmsoup]

Impact or Detonation are my guesses