Blown up RM80. Help required

[A&R]

At the WMCC event on saturday took the newly acquired RM80 along for the son to get to grips with. He had a ball on the green and yellow tracks- twice on each. Decided to attempt the red track. ( should have done it earlier) However he was tired ( only 10yrs old) and kept falling off eventually breaking clutch lever about the 10 km mark - lucky had one in the car but had to go back to get it.

On the way back did a short cut down a fire break he ran out of petrol luckily about 50m from home. However when we filled it up again it sounded awful like something metallic was rattling around in side. Is this what a blown piston sounds like? He was running flat out on the straight when he ran out of fuel. So thought he might have done the damage even before we fuelled up? If so do you usually replace big end ( needle roller brg?) piston rings and gudgeon pin all together. Any help appreciated as new to the modern 2 stroker. Yet to strip down and investigate.

[Danger]

How long did you run the bike for when you heard it rattling? Could have just been an extreme lean condition due to running out of fuel. Remember it is the oil in the fuel that lubricates the piston and bearings. If it continued after a minute it will need a strip down.
Be thankfull it is not a four stroke. These things are cheap and easy to fix.

[A&R]

Thanks Danger.
Stripped it down friday night/saturday. Piston/small end was fine but the big end was completely shagged! I decide that I didn't want to muck the casings trying to split them and don't have the gear to pull the crank to pieces and put in the new needle bearing so botany honda have got it to sort. The bike was standing for a while before I bought it and I was wondering if the roller brg had got rusty due to condensation and after an hour and possibly the "extreme lean condition" you mention above it gave up. Reckon with parts etc. it will cost upwards of $500 to fix in the end though. The young lad and I learnt heaps stripping it though. Colemans were pretty good to us to allowing us to copy an owners manual, so had at least I had a half a clew of what was gong on.