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I have a 2 year old Craftsman mower with a 21 HP Briggs & Stratton Engine, it has been running fine but last week in the iddle of mowing it suddenly started popping. Engine will run but it just pop pop pop, can't choke it or it will go dead. Idling but popping, I have replaced all gas, inline gas filter and new spark plu....any ideas??

Your valves are not seating correctly . Fuel is being ignited before the exhaust valve is seated .

SONOFADOCKER said:

Your valves are not seating correctly . Fuel is being ignited before the exhaust valve is seated .

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What would cause that, it is 2 years old and has been running fine

We get new machines with 10 hours that do the same thing. Things need to put together by hand, not robots at the factory ....

SONOFADOCKER said:

We get new machines with 10 hours that do the same thing. Things need to put together by hand, not robots at the factory ....

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Is there a simple fix?

Everything is easy to reach . Take pics . Remove the valve cover and take the spark plug out . See what movement you have with the valves as you rotate the engine by hand . The parts are not expensive . You can find the same type repair on you tube .