Small Engines (Lawn Mowers, etc.): Stihl Bogs at full load, air fuel mixture, air mixture

Question
John,
I have a Stihl 011 AV Electronic that belongs to a friend.  He reports that the saw runs fine until under load then it bogs down.  I have checked spark, and cleaned the muffler.  I have disassembled the carb, and cleaned it, but I find something interesting.  Reading your responses, it seems I should be looking at the high circuit adjustment, only this carb (a Walbro WT 323A) has no high circuit adjuster.  The "H" port on the carb has been plugged off, clearly at the factory because there aren't even threads for a screw there.

My question is this; on a carb without an "H" adjuster, how do I adjust the high speed?

Dan  

Answer
 Hello Dan:

 This is a Newer Carburetor and Doesn't have a High Air/Fuel Mixture Screw. If you Soaked the Carburetor Overnight in Cleaning Solution(Gunk Carburetor Cleaner) and Blew Out the Passages With Compressed Air and the Carburetor is Still Not Working Properly, then the Carburetor will have to be Replaced. The Carburetor Changes are All About Money for the Manufacturers. That is the Reason for Doing Away with the Air Mixture Screws on the Newer Carburetors. Most of the Newer Carburetors Now Don't have Either Air Mixture Screws. Try Turning the Low Air/Fuel Mixture in 1/4 Turn Open and See if this Helps. On Some Engines if the Low Air Mixture Screw is Closed too Much you will have the Same Problem. Stihl Doesnt Offer Breakdowns/IPL Online. Hope this Helps. I am here if you Require more Assistance. Let me know what Happens, Please. Thanks.

 Good Luck

 Respectfully

 John