Small Engines (Lawn Mowers, etc.): Lawn mower question, intek, fuel filter

Question
a friend has a craftsman mower with a briggs intek v-twin engine.  It starts up & runs fine except that there is a constant "popping" that sounds as if it is coming from the carb.  It gets louder/slightly worse when the blades are engaged.  I changed air filter, fuel filter, spark plugs & they helped a little.  Could this be valve related?  Or any other suggestions are helpful.

Thank you!

Answer
It could be valve related...did you check the Briggs site, Customer Support?  There is a whole section on checking the valves.  It is pretty easy to check them on your engine.

Briggs link:

http://www.briggsandstratton.com/engines/support/frequently-asked-questions/Engi...

If the valves are fine then start with the carb.  90% of poor performance these days are due to dirty carbs.

Have you ever cleaned a carburetor or checked valves?  Not very hard and the Briggs website is pretty helpful.

Let me know if the valves are alright.
Eric