Small Engines (Lawn Mowers, etc.): briggs 31h777, valve clearance, filter clean

Question
QUESTION: Engine lost power. Has new tune up, 170 psi compression. and runs excellent low or high rpm. Just lost all power during one mowing session. just acts like i went from 18 hp to 5 hp. Please help. (snapper zero turn briggs 31h777 18 hp)

ANSWER: Is the governor working?  See the links below for governor operation.

http://engines.myfaqcenter.com/Answer.aspx?p_faqid=3425&body_0$tbKeyword=governo

http://engines.myfaqcenter.com/Answer.aspx?p_faqid=3435&body_0$tbKeyword=governo

Is the air filter clean?  Did you replace the spark plug?

Let me know what you find when inspecting the governor.

Eric

---------- FOLLOW-UP ----------

QUESTION: Oh yeah, I checked governor first thing, Its fine, It is pushing throttle wide open when it loads up. I tore the carb apart today and blew and flushed out all jets with no luck. But when I pulled valve cover I noticed something interesting, the intake valve does not look like it is opening very much. Do you know how much travel the push rod should have and also what the gap is on the valves.

Answer
This link should help:

http://engines.myfaqcenter.com/Answer.aspx?p_faqid=3441&body_0$tbKeyword=valve

Use the "Engine Check Chart" PDF under "Adjusting Tappet Clearances" for the valve spec.  

DO NOT pull both push rods out at the same time and make sure you know which side of the push rod goes inside the engine block.

According to the Engine Check Chart the valve clearance is:
Intake .003-.005 inches
Exhaust .005-.007 inches

Let me know if the link helps.
Eric