2012 yt3000 Craftsman backfire but won't start

[jbell19]

Correct flywheel and key installed but with the same results, think it's time to shop for a new mower

My mistake, key had sheared added lock washer to flywheel bolt and tightened nut to specs and she fired

 

[bertsmobile1]

It will shear again
You need to remove the flywheel and lap the flywheel to the crankshaft with some extra fine valve grinding paste
Check for any lips or burrs before you start & file them off .

 

[StarTech]

or get a second set eyes on the problem.