Small Engines (Lawn Mowers, etc.): 3.5 Hp Briggs & Stratton problems, briggs stratton engine, briggs stratton

Question
Hi George,
I have a 3.5 Hp Briggs & Stratton engine on a Mower made by Murray that is less than a year old, and is only used once a month, but we live in a vey sandy area. The engine revs fast and slow kind of hunting for the right speed, even after I changed the airfilter, sparkplug and oil. I changed all of these things at the same time. I also cleaned and checked the spacing on the magneto. It has no throttle lever, and does not seem to have any adjustments on the carborator at all. The carb is all plastic exept for the brass gass inlet. By the way, it runs as smooth as silk just before it runs out of gas! Any ideas on what the problem may be?

Answer
ROB,  THIS IS THE GOVENOR DOING IT'S JOB  KEEPING THE ENGINE FROM OVER REVVING.  WATCH THE THROTTLE ON THE CARB WHILST IT DOES IT'S THING AND YOU WILL SEE IT GO OPEN AND CLOSED.  THIS GOVENOR WORKS OFF OF THE WIND CREATED OFF OF THE FLYWHEEL  CHECK AND SEE IF THERE IS ANY DEBRIS UNDER THE STARTER COWLING OR BACK BY THE MOTOR COOLING FINS.  SOMETIMES YOU CAN SLOW THIS DOWN BY PUTTING THE LINKIAGE IN A BIND ONCE YOU LOCATE IT BY BENDING WITH A PAIR OF PLIERS A BIT.

GOOD LUCK,
GEORGE