Small Engines (Lawn Mowers, etc.): Compression B&S 12.5HP 286707

Question
have a Briggs & Stratton 12.5HP L-head engine 286707-4026-01 12-1993. I used my compression gauge and got 30PSI reading. I realize a leak down test is more precise; but, does 30PSI sound a little too low?

Answer
Briggs never publishes compression spec.  According to Briggs, there is to many variables and differences to be able to publish a minimum spec.

A rule of thumb Briggs has always stated for checking compression is to rotate the flywheel counter clockwise by hand, opposite the way the engine normally runs, and if the engine has sufficient compression the flywheel will snap forward in the normal rotational direction.

That said, we check a lot of smaller Briggs engines compression just to get a rough baseline.  We normally see about 35 psi in walk behind more engines...your larger engine should be similar.

Is the engine burning oil?  Low on power?  Difficult to start when warm?

Eric