Small Engines (Lawn Mowers, etc.): B&S surging, head bolts, torque wrench

Question
Hello, I just bought a power kraft 18.5 horse 42 inch cut mower. I know nothing about this brand, but I got a great deal on it.

It was running pretty rough so I pulled the plugs. one looked great, the other had signs of being very rich and had virtually no gap. I re-gapped the plug and it runs alot smoother. The problem now is the motor rpm's are surging. I can look in the carb when this is happening and there is a butterfly opening and closing as it happens. The fuel doesn't look like it's atomizing either, more like dripping. What should me steps be fixing this?

Thank you

Answer
Remove, dis-assemble and clean the carb with compressed air from an air compressor and carburetor cleaner.  Set the air compressor regulator to about 20 PSI. TOO much air and you can blow out the inlet needle seat.

The carb is pretty straight forward.  Just pay attention to the fuel pump as there may be 2 small springs inside.  Careful dis-assembly and a digital camera will help when re-assembling.
Make sure the intake gaskets, bolts and the head bolts are tight.  You should use a torque wrench on the head bolts but you can just use a socket to make sure none of them are loose.  If you find any loose head bolts you will need to torque to the proper specification.

Let me know if cleaning the carb solves the problem.
Eric