What compression reading should I get on this engine? Model: J200STLCEB. I have been browsing online and can't find any solid info. I checked the compression on all cylinders with all the plugs removed and they are reading between 71 and 75 PSI. I know compression testers can read different readings so I made a male to male air fitting and tested it with my air compressor just to see if there would be a difference in the gauges. My gauge read 5 psi lower than my air compressor. So I added the 5 psi to each cylinder and that is how I came up with 71-75. How do I know my air compressor gauges are correct? I don't know but this is all I have. Does anyone know what compression reading I should get on this engine as if it were new?