82 KZ 750 LTD- Top end rebuild

Hello, I have some pictures of my piston and valves. I wanted to see what the community has to say about the color and build up on my piston heads. I don't want to provide too much information off the bat so I can get some non-biased feedback first. I will say I bought the bike four years ago with 400 miles on it. It has set for at least 30 years. I ran through the carbs and it was good to go! It now has 6k miles and one of the cylinders runs 100 degrees cooler than the rest. I have tried multiple things like sync carbs, clean carbs, sync, repeat 5 times! haha, Let me know what you think of the pictures. Side note... I don't know if the top of the pistons is a great representation now since I have been messing with them and they were exposed to mineral spirits.

The photos show nothing unusual.

Did the bike run poorly? Was that cold cylinder dropping out and not firing? How did you go about cleaning the carbs? Did you ungang them, fully dissemble and soak everything in carb dip, including all the small jets such as the pilots nozzles? Did you check the valve adjustment? Perform a compression test after valve adjustment?

I'd venture a guess that it was 2 that dropped out. Did you do a compression or leak down test? Check vacuum individually? Check the spark plug?