Fubar-ed My Yamaha Champ

Bought a Moto 4 ( 100cc) for the kid that was smoking. Got some rings, honed the cylinder, put it back together, ran good, but timing chain was a little loose, I didnt have the tensioner installed properly. Took head back apart, re-did the timing chain tensioners, looked much better.  Started it up, run good, but I forgot to tighten the bolt that holds the timing sprocket on.  It came loose, motor dies of course, but when I put the sprocket back on, it doesnt run at all now no matter what.  I check to make sure its up on compression and align the mark on the flywheel with the mark on the timing housing , still nothing.  Took it apart again, everything looks fine, piston still good, valves actuate fine.

What the heck did I do? Did I destroy the head somehow?  Motor seems to be low on compression now.

Edited by DJH73

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