Small Engines (Lawn Mowers, etc.): briggs&stratton lawnmower motor, briggs and stratton, briggs stratton

Question
my uncle sold me and old 1986 i think dynamark lawnmower.when i got it it didnt do nothing so now i got it running and i had to clean the carbuetor.now it keeps rebing up and down so i need to no how to set the idle screws on it. and how to set all the other screws on it please . thank u very much p.s its a briggs and stratton 11hp .


Answer
Hi Michael,

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 not closing the screw more than you need to.  The low speed mixture screw is set at 3/4 of a turn out.  Adjust that, to give a smooth idle.  The 3rd screw, the idle speed screw, is set to give a low idle speed without stalling.   
If the speed continues to rise and fall, I would replace the carb's governer spring.

Good luck.
Michael