Doesn't look like lack of oil on its own to cause that, to me. There doesn't appear to be seize marks on the piston 4 corners that you usually get. The rings are also reasonably intact Suggesting it ran for a while whilst this damage was happening. Probably only failed when the rings finally gave way by getting munched by the parts flying around in there.
Was it a cheap piston? Looks to me like something has just been flying around in the combustion area. Probably started with a chunk of piston and that kept taking more off the top until one but got stuck down the size. Check your exhuast, it's probably full of bits.
It does look like your spark plug is a bit on the lean side do I would suggest it ran lean for too long which caused the eventual break up of the piston from too much heat. Show us your bore, that will help.
Do you have a sports pipe? What jet are you running? I'd check the operation of the autolube to be safe. When you finally get it back together start with a 250 jet at the minimum and ( following a jetting guide as found on here) jet the carb correctly.
Check your fuel filter and fuel lines for blockages or dirt that's been preventing fuel getting through.
looks like the head gasket has been leaking and the engine was injesting coolant inbetween the areas iv highlighted, the rim around the chaimber is a stained colour due to the carbon from combustion, when the engine is hot & running the down stroke injests cooler coolant this then hits the piston and cools it rapidly causing it to contract and cool loads quicker than the rest of the piston causting it to become brittle and flake off then the bits get bounced round the top end and trapped between the piston and the bore causing complete distruction
similar thing to like when u tip boiling water on a frozen windscreen if ur not carfull it shatteres...like that but in reverse lol
check the head and barrel surfaces for waroage before re using
and use a gen uine hedgasket]check to torque settings then re torque after 1st ride
As above lads ,full chat all of a sudden or built up slowly losing power ,but overall lack of fuel/oil.....or broken seal real fast good luck fella ur in the right place man
looks like lack of oil to me and the spark plug tip looks white from the picture get a few more pics up of the spark plug and the barrel
...dtr macca with the evil eye +1 on this lads ,if it was oil failure or starvation alone it would of had more melted piston as it tightened up ...sudden air leak or deceleration with closed throttle from high speed/temp ..pop
[IMG]
+1 on this lads ,if it was oil failure or starvation alone it would of had more melted piston as it tightened up ...sudden air leak or deceleration with closed throttle from high speed/temp ..pop
