[cmanningjr]

Welcome!
Sorry to hear it. I don't know. Part of me would want to put the chain back on, and run it to see. Another part would want to go ahead and rebuild it, knowing that even if this just happened, something has been compromised. You could always get the oil analyzed, and see where the particles came from. It's possible that they represent manufacturing debris or normal wear and tear, and that the chain just recently came off. Or, you find out that it needs to be rebuilt.
I'd definitely want to know why the chain was off, and if it would do it again.

Chains on these things are loose and rattle, some people think it's normal...I don't.......

 

[cmanningjr]

You'll have to remove the head to keep the cam followers from falling in the engine.. All you'll have to do at that point is to pull the cylinder and inspect the walls and piston for damage...Couple of new gaskets, hone and some new rings, you should be good to go..Flush out the bottom end, new oil filter...Maybe, No more than it was ran, there's no bottom end damage....

 

[cmanningjr]

That sucks. I would think the chain couldn't possibly have been off very long. Without the oil pump running the top end would lock up within seconds. Seems very odd it was still running.

Rob

I agree........