My craftsman 13 1/2 hp briggs&straton rider will not start. I changed the spark plug,gas and checked for spark. It seems that the spark is light but I'm not sure. Thank you austin.

Could you define "light spark" please. And what were the symptoms leading up to this problem? With more info. We may be able to help you out.

Light spark should be fine. It should still do the job. Remove the air filter, spray some starter fluid to the carb and try to start the engine. Let me know if there are backfires or smokings.