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What should the compression be?

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just4fn
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2025/07/14 23:32:03 (permalink)
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What should the compression be?

I have a toro 7.25 HP mower.  I think is has a decompression cam.  What should the measured compression be?  I'm getting 40lbs.  I think that is ok with a decompression valve but not sure. 
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    SRTsFZ6
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    Re: What should the compression be? 2025/07/15 06:28:44 (permalink)
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    40 is super low...
     
    Can you post an engine model #????
     
    .

    Scott
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    just4fn
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    Re: What should the compression be? 2025/07/16 07:28:31 (permalink)
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    model # 128M02-0017-F1
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    SRTsFZ6
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    Re: What should the compression be? 2025/07/16 15:25:58 (permalink)
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    https://www.jackssmallengines.com/jacks-parts-lookup/manufacturer/briggs-stratton/briggs-stratton-engine/100000-19z999-series/128m00-to-128m99/128m02-0017-f1
     
    That model # is showing a "flat head" engine-NO overhead rockers. 
    I don't believe they had a flat head engine that large..
     
    IF it is a FLAT HEAD engine, check  / tighten the THREE HEAD bolts CLOSEST
    to the exhaust valve.  They loosen up (very, very common) and will cause
    no start issues...   
     
    About 15' lbs on the head bolts.  
     
    If you have an overhead valve engine, advise.  I own a 7 HP Briggs OHV
    engine and can get you a pressure #...   Advise..
     
    .

    Scott
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    just4fn
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    Re: What should the compression be? 2025/07/16 19:16:11 (permalink)
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    Thanks for the info.  I will look at it this weekend and report back. 
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