B&S 25hp Surging

Old 04-29-08, 11:38 AM
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Unhappy B&S 25hp Surging

I have a Statesman branded MTD lawnmower equipped with a 25 hp Briggs and Stratton engine. The engine model is 445777, Type: 0122 E1 and the code is 010104YH. The mower was purchased by my father in 2002 and the engine has been in good working order since.

This year has been a bad year for the lawnmowers. On this particular machine, we had to remove and replace (R&R) the fuel lines and pump. Once we got the fuel system repaired, we were able to get the engine to start only for it to begin surging quite strongly. Its okay until you hit 2/3rds throttle but after that, it surges no matter what the throttle is set until you shut the machine off and restart it. I have no problems with starting or shutting the engine down.

I did take the carb bowl off and drain the old gas, but did not have the chance to clean everything else in the carb. From the sounds of the other posts on this forum I may have to overhaul the carb or at least give it a thorough cleaning.

Any suggestions or recomendations? I do not have the repair manual for this engine, only the parts list. Any help would be greatly appreciated. Thanks.
Old 04-29-08, 05:20 PM
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Join Date: Apr 2004
Location: Upstate New York
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Surging (or commonly referred to "governor hunting") is a result of a lean carburetor condition. You need to remove and clean out the two main jets. If this alone doesn't take care of the problem then you'll need to remove the entire carburetor and soak and recondition it. If you'd rather just replace the main jets they are Briggs part number 690232.

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