I have a craftsman riding mower. It was working fine and then it shut off because the blades became jamed with too much grass. I cleared the problem and now it won't start. I have replaced the battery and plug. It cranks and sometimes backfires but it won't turn over.

Hi,
Backfiring generally points to a valv or timing problem. Is it a Kohler; suspect flywheel key.
Peace,
Clarke