Small Engines (Lawn Mowers, etc.): Engine trouble, bottom side, engine trouble

Question
I have a briggs 20 hp twin. It wonts to run on half choke. When I push the coke all the way in it idles up and down.

Answer
In general, you need to take apart the carb and clean out the main
jet.

If it is the old l-twin, you can access the main jet by removing the plug on the bottom side of the carb and fuel will dribble out a little, that will take a 5/8 wrench.
Inside the hole is the main jet, you will need an allen head wrench to remove, 3/16 I believe, remove it and clean it, reassemble, that
should help the engine, there is a low mixture screw on the front that can be turned out a little as well.
   If this isn't your engine, please find and post your engine's model numbers.