Flybrandon Posted May 30, 2020 Report Share Posted May 30, 2020 650 hr 250 SHO what should the compressions be? Quote Link to comment Share on other sites More sharing options...
jh141 Posted May 30, 2020 Report Share Posted May 30, 2020 Manual says 'Minimum" compression at 68 degrees, wide open throttle, all spark plugs removed = 104.4 psi As a norm I am looking for the same compression in all cylinders. Though I have never needed to check my SHO, I would expect to see 140-160 psi on a good motor. Last motors I compression checked was a pair of Yamaha F250s and they were bumping 155 plus on my gauge and were all within 4 percent of each other. Those were very good motors with a little over 1000 hours each. They are still pushing a 26 foot safe boat around years later. Quote Link to comment Share on other sites More sharing options...
Robert3 Posted June 1, 2020 Report Share Posted June 1, 2020 I had a older 2010 SHO250, it blew while i was 30 Miles from home, thrust bearing issue.. I had checked the compression, and leak down ( MORE APPLICABLE) 160psi on all jugs, one cyclinder had more than 50% leak down... Yammy cover it on a 3 year outta warranty engine, long block replaced.. I just bought a new one anyway, my dealer rcvd the benefit, which is great Now my new one has 700 hours on it, doesn't make oil, runs like new everyday Quote Link to comment Share on other sites More sharing options...
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