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Curtis B.
Curtis B., Technician
Category: Small Engine
Satisfied Customers: 26027
Experience:  have worked on and around most engine models for 35 yrs./Polaris ATV expert
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I have a Craftsman sit down mower with a Briggs and Stratton

Customer Question

I have a Craftsman sit down mower with a Briggs and Stratton 24 HP 724 Platinum Engine. 200 hours approximately. Has been maintained regularly with tune up and oil changes, deck cleanings etc. I am a mechanic by trade myself. It developed a sputter last during the last lawn cutting, smoothed out and I was able to finish, but starred the same symptom as I started to put it away. It takes about 2 hours per cut. I had no engine stalls, and no problem restarting. I have noticed recently, an occasional backfire when restarting hot. I have not checked it out yet, and was hoping to be pointed in the right direction before I start replacing parts. I ALWAYS add Stabil before winter storage. I am several weeks into the current cutting season, when the troubles started.
Submitted: 5 months ago.
Category: Small Engine
Expert:  Curtis B. replied 5 months ago.

With twin engine I always run a cylinder balance test. Loosen the spark plug wires and with engine idling, remove one wire at a time, engine should continue to run. If it dies when either wire is removed, the opposite cylinder is not firing. If both ok, Have the valves ever been adjusted? Valves may be too tight, causing misfire when hot. Lash needs to be .004 to .006 inch.