Small Engines (Lawn Mowers, etc.): B&S 18.5 Hp OHV Engine, air fuel mixture, adjustment screws

Question
I Have A 18.5 B&S OHV Engine Model # 31P777 Type # E348 E1 Code # 040922Z0 The Engine Is Back Firing out Of The Carb Only At Normal Idle  Usually. Their Is Only 2 Adjustment Screws The Idle & The Air & Fuel Mixture Which Can Only Be Turned So Far Each Way . How Do You Remove This Carb For Overnight Cleaning If That Is Possibly The Prob? Their Is 2 Wires Connecting To The Bottom Of The Bowl & I Am Not Familier With Removing The Carb On A Mower. So This Is My First Attempt At This. I Have Adjusted Both Valves & They Are Both Appear To Be Opening & Closing The Same.  It Starts Ok Just Has A Backfire In The Carb

Answer
Gary,

   Sounds Like the Carb needs a simple overhaul removing this Carb assembly is best done by someone who had done this before due to the fact the 2 wires are grounds from the Stators in the engine Unless you have serviced OHV engines in the past this is not something you will want to get into on your own.
the OHV engine is Not like your average Engine the parts are far more expensive to replace if you accidentally break one But the carb is assembled basically in the same way a normal engine is built Depending On style You Have either a Walbro or a Nikki I am going to give you a Link that will open a shop Manual for this engine so you yourself can see this is a job for a professional.
http://www.briggsandstratton.com/pdf/illustrated_parts_list/100/MS5766.pdf
As for the back firing to help ease this problem try using fuel injector and carb cleaner added to your Gasoline since i Dont know the size of your fuel tank normally I use  1/2 a Bottle to 5 gallons of Gas run it completely thru your  engine about 2-3 times per season
Try using the cleaner first If this problem persists take your Mower into a shop for a carb Overhaul Please Dont try to remove the carb yourself I have seen the costly end results of someone trying to do this on their own and it winds up costing them $300.00 Plus to fix their mistakes.
Best Tip for you when seeking a shop to repair your OHV Engine
Ask the shop Do they specialize In this Model and series of engines and are they an Authorized B&S Repair Center.