Up & Runnig Sort'of

Built a mb W/ my 14 y.o. son as his Christmas present. Have logged quite few hours in the garage fine tuning & tweeking the setup on his beach cruiser. We are having trouble keeping it running, a carby issue. The carb is flooding and fuel backing out thru the air filter. have dis & re assembled the carb. Tickler is NOT stuck (we don't use); float is free; air/fuel mix screew has been seated & backed out 3.5 turns; carb is nearly perfect level to ground. OF NOTE: fuel floods thru that air filter even when not running until shutoff valve turned.
Need to gets the machine to go & keep it going for my young man.
Any suggestions???

Thx, I am new to blogging so sorry for doing so x2. When I had the carb apart it didn't look like the float needle was easily accessed but has to be for a rebuild. Can I do anything to ensure free movement short of returning for replacement under warranty? BTW float did not have any fuel inside.