Small Engines (Lawn Mowers, etc.): sthilchainsaw, stihl saws, carburetor body

Question
I have a sthil 041 av chain saw. its probably older than me. its always started in 3 pulls even if it sat for more than a year. but i let my dad have it for the last 3 years. i recently got it back and had to weld the block where the carb gets bolted. I also put new gaskets and diafram when putting carb back on.it still starts in 2 to 3 pulls but i cant get thethe cab set right. one minute it runs fine and the next time you start it its reving or it wont idle. can you explain this? can you tell me the correct setting for the high and low settings on the carb?I had it set once ,it idled great and reved up perfect but it whent thru a tank of gas in minutes. when i re checked the carb it was loose so i tightend it and when i started it up it screemed. yet i didnt touch any adjustments. and when i tried to idle it down it whent from fast to dead stop.  can you help?  just to let you know i bought tis saw for $50.00 dollars at a yard sale 22years ago and have never had to pull it more than tree times to start it.      it is a 041 av  stihl 12  91110 084 0910

Answer
Hello Dean:

You have a Great Saw. The Older Stihl Saws were Great Saws and Gave Little Trouble Compared to Todays Stihl Saws. Remove the Muffler and Inspect the Exhaust Port for Carbon Blocking the Exhaust Port. Check the Muffler and Spark Arrestor Screen (in the muffler) for Blockage Also. Check the Jug Bolts and be Sure they are Still Tight. Also,  Remove, Disassemble and Soak the Carburetor Overnight in Carburetor Cleaner (I Use Gunk). I have Found that Most People can Use a Breakdown/IPL and Disassemble the Carburetor Enough for Proper Cleaning. You Only have to Remove the Bowl, Float Pin, Float (if Applicable)  and Needle Valve and Any Adjustment Screws that Go Into the Carburetor Body. The Welch Plugs Do Not have to be Removed. Then Soak the Carburetor Body and Parts in a 1 Gallon Can of Gunk Carburetor Cleaner Overnight. The Can has a Parts Tray Inside it for the Small Parts. Once the Carburetor and Parts are in the Cleaner, you can Replace the Lid for Safety and to Prevent Accidental Spillage. Then Blow Out the Passages with Compressed Air. Install New Parts if Required. ****All the Carburetor Adjustments are the Same for Lawn Mower and Trimmers. There are Several Location for the Air Mixture Screws. The Idle Air Mixture Screws are Usually Located at the Top of the Carburetor Bowl and the Top of the Carburetor Body. If the Main Air and Idle Air Mixture Screws are Side by Side on the Side of the Carburetor, then the Idle Air is the Farthest from the Engine. The Main Jet Air Mixture Screw is Located in the Bottom of the Carburetor Bowl or Beside the Idle Air Screw on the Side of the Carburetor Body. Some of the Older Model Carburetors have the Main Jet Mixture Screw Straight in from the Top of the Carburetor Body (this is Rare anymore). If you have Cleaned the Carburetor (Disassembled and Soaked Overnight in Carburetor Cleaner (I Use Gunk). Then Blow Out the Passages with Compressed Air and Install a New Kit if Required. Now Setting the Air Mixture Screws:  ****Turn the Idle Air and Main Air Mixture Screws In Until SNUG **Do Not Jam** Then Reverse Both Screws 1 1/2 Turns. Holding the Throttle Full Open, Start the Engine. Turn the Main Air Mixture Screw Clockwise Until Proper Revs are Obtained. Occasionally you May have to Turn this Counter Clockwise to Achieve the Proper Revs. Now Allow the Engine to Idle. Set the Engine Idle Screw (Not Idle Air) so the Engine will Stay Running if Required. Now Set the Idle Air Mixture Screw so there is No Hesitation when Throttling from Idle to Full Throttle. Reset the Engine Idle if Required.**** You have Been Lucky that the Carburetor has Not had to be Cleaned Before Now. Usually the Carburetor has to be Soaked and Cleaned Every 3 to 5 Years Unless it is Used Every Week. Stihl Offers No Online Support Other then a Dealer Locator. If you Hit a Snag or this Does Not Correct the Problem,  I am Here if You Require More Assistance. Hope this Helps. Let me Know What Happens, Please. May the All Mighty Bless You and Yours. Thanks.

Good Luck

Respectfully

John

PS: I am Allowed to Answer 10 Questions a Day. If you See I am Maxxed Out, then Try Submitting your Question at or Just After 8pm EST (US). My New Day Starts then. Thanks.

Respectfully

John