Question about Briggs & Stratton Lawn-Boy Insight Series 21-Inch 190cc 650 Series Gas Powered Engine Variable Speed Self-Propelled Lawn Mower

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B & S 10D902 lack of compression when starting

Caught ant hill when mowing - now when pulling starting handle seems like a lack of compression - engine not even trying to start as though no spark reaching mix.

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  • martin wells May 05, 2010

    Took plug out, put finger where suggested, pulled handle, felt compression - replaced plug, pulled handle, engine started - complement you on your genius :)

  • martin wells May 05, 2010

    P.S. came in to write that it started - went back to cut the compression, again ! Help!!!


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May have broke crank newer mowers are not built as they use to be take out plug and place finger over hole to test for compression if none u broke more than likely the crank

Posted on May 05, 2010

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Check the flywheel key ( also referred to as a shear pin). It's an aluminum key that keeps your flywheel in time with your crankshaft. It is designed to shear when the engine is met with a sudden, strong opposed force in order to keep the engine from being damaged. When it shears, it throws the engine out of time, hence it won't run. Good luck.

Posted on Aug 19, 2012

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Lack of power

You should try doing a tune up change spark plugs, wires, pcv,and fuel's reasonable to assume that the rings and
valves (inside the engine) have become worn. Worn rings
and valves will cause the engine to have low compression
and low compression = weak power.
You may be curious as to why the engine's lack of power is
most evident when driving up a hill. Well, when a vehicle is
going up a hill, the engine is under more stress than when
driving on a flat road. Therefore, any wear in the rings/valves
will tend to be revealed - in the form of compression - when
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you will need to have a mechanic verify that the rings and/or
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If the mechanic tells you he positively confirmed a worn ring
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