Small Engines (Lawn Mowers, etc.): 18.5 horse power Briggs & Stratton Carb Linkage, briggs stratton, speed jet

Question
My ten year old mower engine surges except at high speeds.  I have changed spark plugs and adjusted the carburetor and noticed the linkage is loose with the throttle set at low speed.  The springs look okay, but I suspect the linkage is the problem, how loose should the linkage be?

Answer
I have seen some pretty loose linkages run fine.  Have you cleaned the high speed fuel circuit.  There is a bolt/screw on most of the L head twin carbs that you can remove without dis-assembling the entire carb.  Removing the bolt/screw on the located on the lower half of the carb will provide access to the high speed jet.  Blowing air from an air compressor through the high speed jet will often solve the surging problem.  

Completely dis-assembling and cleaning the carb is the preferred repair method but just cleaning the high speed circuit may solve your problem.
Let me know if this helps.

Eric