Troy bilt, MTD, Yard Machines, Toro, Bolens, Craftsman, Honda lawnmowers shouldn’t backfire when you’re trying to start them. This often is a sign that the mower is damaged in some way; for example, you might have run over a large rock or other obstruction. When a flywheel is broken, your mower might stutter or backfire when you try to start it, but it won’t completely engage.