You're running a bit rich, best out of the set is number 2 and 4. See how there is a lighter bit to the base ring? Thats how they should look, it needs one full turn of colour like that. Since the electrodes are pretty clean I'd say your rich down low. Try a quarter turn in on the pilots and a good carb sync and see how it goes. The reason it's lumpy is number 1 is super rich down low(sooty base ring and electrode tip) and the rest are fairly even though 4 is a bit lazy. A carb sync will help if any of the other cylinders aren't pulling their weight. Turn the screws in 1/4 turn and sync that should lean it out enough to get rid of the soot and even the pulling of the cylinders. Number 1 is basically doing most of the work and dragging the other cylinders along for the ride. So you get an abnormally stong push from number 1 cylinder then a weak ass push from the other cylinders so I'm assuming your bike would be like lumpity-lumpity-lump like a Harley than a smooth inline four. Maybe double check the float height on number 1 cylinder. If its good and it's still rich you can lean it out a tad by either turning in the mixture screw on that cylinder in or raising the float height a mm or so so it's not overfuelling. But before any float adjustments, turn the mixture screws in a 1/4 turn and do a good sync. It will probably unitize the cylinders a bit better.
When you're doing a sync concentrate on pairs. Do 1 and 2, then 3 and 4, then adjust the centre adjuster to sync the pairs together. Also once you have a pair synced give it a good wack on the throttle and let the throttle snap back to idle a few times so that it seats the adjusters on the stops then check again. You don't want it wandering after you've put the bike back together.
What jets(pilot, main) are you running and how many turns out are you on the mixture screws? Shims?
