My Bolens 15.5ohv B&S mower seems to have 2 much compretion and will not start. Took spark plug out and had gas to come out.when plug is out it turns over fine,put it back in it tries to turn over but want,Already check the batt

It sounds like you need to adjust the valves on the engine. It will cause it to have too much compression to turn the engine over.

This video will show you how to do it:

YouTube - IFIXIT4U's Channel