I have let friends ride my ATV's, and if something broke or tweaked from a crash I have never asked them to pay for it. However they have always offered to fix it.
I have always fix any thing I broke also.
He or his dad should offer to fix it.

 

Welcome to the forums.

Legally, they don't have to do anything since you have nothing signed beforehand. The argument could be made that he made a verbal contract when he said he'd be careful, but unless he also said he'd pay for any damage, that wouldn't be of much help.

I would think that they would also step up an pay for something they broke. It would just be the right thing to do.

Do a good check of the suspension and steering stem. Those will take most of the damage in a roll.

If you don't mind used parts, ebay is a good place too. Gotten quite a few parts that were used, but still in perfect shape to fix exactly what you're going through.

 

Sam gave you his word and still broke it. Its his fault and he should pay for it. My only thing to say to you is you should definitely be a little more cautious and only let people with experience ride your atvs. He broke he pays for it. simple as that.