Suddenly fouling plugs

I've suddenly started fouling plugs, and i'm completely stumped. A little background here......

I've always been running slightly rich, but all of a sudden I started getting tons of black smoke out of the left pipe. I played around with the mix a bit on the 1 + 2 carbs. No change, so then I pulled the carbs off, I started to tear into them. first thing I did was pull off the #1 bowl and a jet was in it. Figured I found my problem. While I had the carbs off, I pulled out all the jets and made sure they were clean, and cleaned out the bowls and pilot circuits quickly. The bike was running fine before, a little bit of varnish in the bowls, nothing bad. I did an extensive "in the church of clean" cleaning over the winter. Also, while i was working... I decided to get a new battery. It's a couple years old and starting to be a little flaky on the starts. I upgaded from the standard lead acid to a sealed gel battery. Now, I'm running WAY rich and fouling plugs on the 1, 3, and 4. I don't know what I did. I didn't touch anything on the 3 + 4 side. Any ideas? Help! thanks!

 

PS, the black smoke is now gone.

 

My problem has been with the pilot screws. Since you gave them a quick cleaning, you must have removed them. My J700 pilot screws are now set anywhere from 1 to 1 1/2 turn open. Any more and I get black plugs, not to mention poor mileage.

 

I didn't touch the pilot screws on 3 +4 until I started fouling plugs. I wonder if that quick clean just opened something up enough to let a bit more fuel through. This bike was last on the road in 1990, so there was a load of scuzz build up everywhere...... I'll try turning them in and resetting. Off the top of my head, i think they are about 2 1/2 - 3 turns out.... I burnt through about 3/4 gallon in about 45 minutes on idle (SMH)

 

Make sure you have the correct plugs in also.

 

If you didn't remove the screws, but blew them out with carb cleaner, you may have damaged the small o-rings, and that would really allow a lot of fuel in. Fitz doesn't like my term "temperamental", so let's just say that I have found these Hitachi carbs to be very "sensitive" to any changes. That's why I am adjusting slowly until I get the perfect color plugs.

I'm afraid that my XJ700N is just a gas hog. My carbs are spotless, and I'm still adjusting down my pilot screws on # 1 & 2, and I don't think I'm anywhere near the 46 mpg advertised.