Small Engines (Lawn Mowers, etc.): Stihl chainsaw flooding, gasoline brands, air mixture

Question
John,

I have a Stihl model 021 that has performed flawlessly for three years.  Recently though, it has developed a habit of starting normally the first time in the day, but immediately begin to flood.  Keeping it reved up good will allow you to keep cutting, but the moment you let it slow down, it floods out and dies.  The only way to restart is to remove the plug, blow it and the cylinder out really good with compressed air, and start the procedure again.

I can remove the carb, tear it down, soak it in alcohol, and reassemble it.  Although I've never found any trash in it, that fixes it for all of that day.  It runs good and idles good.  The next morning, however, the process starts all over again.  What do you think?  I've washed out the tank, and changed gasoline brands. I only run Stihl oil in it.

Answer
 Hello Terry:

 I've Never had Much Luck using the Alcohol for Carburetor Cleaning. It Doesn't Loosen the Varnish. Carburetor are Hard to Clean. I Suggest the Carburetor be Soaked Overnight in Carburetor Cleaning Solution (I use Gunk) and then Blow Out the Passages with Compressed Air. Install New Kit. The Following it Instructions on the Air Mixture Screw Settings. Read the Entire Text before Setting the Air Mixture, Please. **The High Air Mixture Screw is In the Carburetor Bowl in the Center of the Nut or Some Carburetors have Both the Low and High Side by Side on the Top Side of the Carburetor. The Screw Closest to the Engine Is Usually the High Air Mixture Screw on this Type Carburetor.The Low Air Mixture is the One at Top on the Side and Goes Into the Carburetor.   Some have the Idle Air Mixture Screw Going Vertically Into the Top of the Carburetor. The Idle Screw is the One that Moves the Throttle Plate. The Following is the Directions for Setting these Screws. **If the Carburetor was Soaked Overnight in Carburetor Cleaning Solution and the Passages Blown Out with Compressed Air and a New Kit Installed,  then we can Set the Air Mixture Screws. Turn Both Air Mixture Screws In Until Seated. **DO NOT JAM  SNUG ONLY** Turn Both Screws Out 1 1/2 Turns. Set the Throttle to Full Open and Start the Engine. Override the Throttle by Pushing the Governor Arm by Hand and Turn the High Air Mixture Screw(bottom of the bowl) In Until the Engine is Revving Properly. Now Slow Engine to Idle. Set the Low Air Mixture Screw so there is No Hesitation when Throttling from Idle to Full Throttle. Now Set the Idle if Required.** Hope this Helps. I am here if you Require more Assistance. Let me know what Happens, Please. Thanks. Be Safe.

 Good Luck

 Respectfully

 John

 PS:  Happy Thanksgiving and Merry Christmas (:-))