bike is popping whenever driving

[98_600]

I have a 98 katana 600 with 25000 miles. When I got it, i pulled the carbs apart and completely cleaned them and resynced them. I also adjusted the valves.
I put ngk iridium plugs in it, but had a slight problem with them. Cylinder 2 would fire sometimes and cylinder 1 wouldn't fire at all. I put standard ngks in it and now they all fire when they are supposed to.
After I did all that, it ran great. Then a few days ago, it seems to be backfiring quite a bit. As I am driving down the road, it will pop out the exhaust. It will keep doing this. With the choke all the way on, it doesn't do it. If the choke is any less than 3/4, it pops like crazy. It is getting really annoying.
I was told to richen one of the carbs up and resync them all to that one.
Any suggestions? I am at a loss. I think it might have something to do with timing, but am not sure. Bikes are a bit harder to work on than cars.
Please help me out, this is my only transportation till I get my truck back on the road.
Thanks

[steves]

It might be an after-fire caused by a lean condition.

What are your float levels and A/F screws set to?

http://en.wikipedia.org/wiki/Back-fire

[GregS]

Was this misfire there before the carb work? My first guess would be something was missed in the carb cleaning.

[1990gsx 600]

my bike pops when i rev it in neutral of course i still dont have a can for it..... but i have the AF screws set at 3 turns out just because of that

[98_600]

It ran great after I cleaned the carbs.
I'm pretty sure it is running lean. Tomorrow I am going to check the carbs out and go from there.

[98_600]

So I ran into a bit of a problem with the bike starting when I went to bring it in the garage to check the carbs. It had no spark. So after a couple days and a bit of frastration, I changed the plugs and it started.
So my a/f screws were all between 2 1/2 and 2 3/4 so I changed them all to an even 3 turns. I got it all put back together and it started right up. Once it was warmed up, I hit the throttle a few times and it was hesitating to begin with. Thats running rich right?
Also there is now a bit of smoke coming out the exhaust. More when I hit the throttle. It also pops slightly while sitting there running.
Maybe I should put all the a/f screws at 2 3/4 and see what happens.

[steves]

I would set the screws at 2.5 turns out and go from there.

[98_600]

That is where I had them before.

[98_600]

Ok, me and my buddy took some exhaust pipe temps after my ride home from work. There was a pretty big difference between the four. We checked it a couple inches down on the pipes fron the head. The readings from left to right were 162, 231, 293, 263. We are going to mess with the carbs and see what we can do.
Any ideas?