First start running rich/backfiring

I have just reinstalled my carbs after a thorough cleaning. I am now backfiring at idle on cylinder 1 or 2 not sure and exhaust fumes smell of large amounts of fuel. I'm curious if anyone can suggest if I should be looking at fuel screws which is set to how they were stock or ignition
Etc.? I have slip on mufflers which were not on originally if that makes a large difference at idle I suppose not.

Did you check the fuel level in each carb using the clear tube method?
Did two of the sparkplug wires get installed on the wrong spakplugs?

I have done the clear tube method multiple times and i found that I had cracked over flows. I went ahead and soldered the over flows and set the bowl heights to spec. I Will double check spark plug wires also but I'm certain it may be something else. How often do the ignition systems fail on these bikes I have read a few things on here that suggest it's common but this bike only has 7000 miles on it of course it's a 1980 so age is its biggest enemy. Is there anything else I can check to gather more info? Spark plug's 1 and 2 were black and smeled of gas.

Disconnect the plug wires and look for green crap on the ends. If so nip 1/4" off the ends and put them back on.
Steve