82 kz550 ltd

So when I was riding for 15 mins today I notice my engine will make a popping sound when I let off the throttle quick and it well pop when it sits idle when I get home. I checked spark plugs and # 4 #3 #2 seems to be fine in color, not much black on the white insulator but then I take #1 plug out and noticed the insulator is black and the metal on the bottom of spark plug is alil black too, is this a result of #1 cylinder running rich?

Sounds like they're all rich. Valves adjusted?
Steve

I haven't adjusted the carbs yet

Carbs are the last thing to be adjusted.
Steve

Well can't adjust the valves because they have shims and can get to the unless to take the cover off

Do you have a manual?
Steve