Small Engines (Lawn Mowers, etc.): Stihl BR-420 will not start, stihl br, br 420

Question
Hello Ben,
I have a Stihl BR-420 that will not start.  It appears to have good compression.  The carb is a Walbro HD28A.  I have verified I have spark but have changed the plug to a new Champion E3. I have changed the fuel.  I purchased and installed a carb reuild kit which includes the screen, needle, diaphrams etc.  I have run a twist tie wire through all little holes I could find before reassembling it.  Finally, per a Walbro manual I found online, I adjusted the idle and high adjustment needles (screws) to open 1 1/4 turns) because the previous owner played around with them.  I am wondering if there are points that could be affecting this or if it may be flooded and if so I do not know how to effectively drain, ensuring the cylinder is also empty of fuel.  Or am I missing something else?  Thanks in advance.

Answer
Bruce

You may have a air leak somewhere around the carb causing a poor source of fuel going into the carb.Try opening the spark plug port and letting the fuel dry naturally or blow some compressed air in the hole. If you have that much fuel in the cylinder head there has to be a leak somewhere.
Allot of times the exhaust gets clogged up with carbon,try taking the exhaust and cleaning it you can use carb cleaner but do not try to start the engine right away you just get a big bang or a big flame.Let it dry for a while.