How To: Check marine outboard engine compression?

The psi compression reading will increase a little each time the engine cranks over. So you can record the reading you get after five cranks of the engine and compare that reading to any other cylinders. A good automobile engine should produce over 100 psi by the fifth crank of the engine in my experience depending on how well the cylinder walls are lubricated to start with. Many readings are 120 to 150 psi on the fifth crank of the engine.