Small Engines (Lawn Mowers, etc.): B&S 4hp mower engine sputtery, lawnmower engine, carburetor

Question
I've got a B&S 4hp Quattro lawnmower engine that is about 5-6 years old. It has run pretty well, but now is running pretty rough and guzzling gas. I only mow once or twice a month, change the oil and feed it a bottle of carb cleaner at the beginning of each season, and clean the air filter when it's dirty. I'm wondering if the carburetor needs to be adjusted, but I don't know if it can be, or how to do it. There is no throttle, and the mower is a simple pusher.

Do you know what the most likely cause of the sputtering and gas guzzling is? If it is the carb, can it be adjusted, and if so, how?

Thanks for your help.

Answer
Hi Ben,

Sure, try adjusting the carb.
The high speed mixture screw is initially set at 1&1/2 turns out.  Then adjust it to give good acceleration and top speed while keeping the screw as far out as possible.  The low speed mixture screw is set at 3/4 turn out, then adjust to give a smooth idle.   

Good Luck.
Michael