Popping thru carb.

swest wrote: Do the thumb test first.
Steve

Not familiar with thumb test. Lol

The sooty plug points to maybe either too rich on the pilot circuit or ignition misfire? Try swapping your HT leads from 1 to 4 to eliminate the (unlikely) ignition misfire possibility.

The sticky slide seems more likely the problem, you can polish the slides and bores lightly with fine wet and dry; up down vertical strokes only and lightly. Needles can get slightly bent, and emulsion tubes do wear. Check that suspect carb very carefully, you could even swap these needles and tubes when rebuilding the carbs to eliminate this possibility.

Taking off the pods would lean the mix, so jetting probably not too rich overall. I think as you suspect you are probably lean on 3 but very rich on one. ..the sooty one that is miles out with the sticky slide issue.

76KZ900, Sounds like you might be experiencing the same issue I had on my Kz1000P. I had popping at idle and, the bike only ran decent once I got up in revs. I was going nuts because I figured it was a carburetor issue so, I took them off quite a few times until I got it right!
Bottom line, I switched out the pilot jets from 37's to 40"s. I am running 4 into one exhaust and also am running pod filters. I did not change out the main jets. Bike runs VERY strong! Good luck with your bike. FYI, if you have messed with the air screw adjustments, you might want to readjust them to a baseline adjustment of 1 1/2 turns out. Once you install replacement pilot jets, start the bike and see how it idles. I left my air screws at 1 1/2 turns out for now. When I first fire the bike up with the choke on, I get a minor pop or sneeze from the carbs but as the motor warms up, the popping/sneezing goes away. guess I could adjust air screws to fully eliminate the popping during warm up. Again, my bike has very little pop so, I might not mess with adjustments because the bike runs very strong as it is.

What I found do far.. The carb that is popping and has sooty plug. Had slide stuck up.. And was missing vacume plug on port used to sync. I'm assuming it came off during one of the popping or sneezing episodes. All I have got to do is start bike.. Started up no popping or sneezing even when engine was cold. Pilot jets should be here tomorrow. I'll install them this weekend and see how it runs. Thanks for all the input.