Small Engines (Lawn Mowers, etc.): B&S engine surge, hp briggs, sediment bowl

Question
I have a 5 year old, 6 hp Briggs engine on a Sears lawn mower that has been surging for the last mowing season. It has a flyweight governor.  The linkage is free and moves freely.  I removed the carb., removed the sediment bowl and used compressed air to blow through all areas.  I find no air leaks and find no carb. adjustments that could be made.  Any ideas on what is causing the surge?

Answer
 Hello Ray:

 It Sounds Like Varnish has Built Up in the Main Jet and is Restricting the Fuel Flow. Blowing Out the Carburetor will Not Remove this Varnish. Disassemble and Soak the Carburetor Overnight in Carburetor Cleaner and Then Blow Out with Compressed Air. Hope this Helps. I am here if you Require more Assistance. Thanks.

 Good Luck

 Respectfully

 John