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1980 kz440B only one cylinder firing during idle

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09 Mar 2021 12:58 #844624 by eergin
Hi Folks

I am working on a 1980 kz440B. It is idling on one cylinder only. The second cylinder fires and cuts out as I ride at higher rpms. Here is what I have done so far:
1- Checked the spark and swapped the wires. Still the same cylinder not firing
2- Checked the plug, it is looking wet. Like flooded (This suggests maybe the float needs adjusted)
3- Removed and cleaned the carbs. Went thru the jets. They were clean but still cleaned them more
4- As I was working on the carbs I got the nonfiring carb to fire but only when I actually block the feed to the originally working carb. Essentially I put some chemical which clogged the fuel line to the working side and this caused the firing sides to change. When I unclogged it I am back to where I started.

I am wondering if the carbs are so out of sync that only one cylinder works at a time. Is that possible?

BTW as I was cleaning the carbs I adjusted the throttle plates so they are perfectly aligned. I assumed that would be a good starting point before doing any syncing as the bike was running.
One more thing, the choke spring mechanism is quite loose, it does close the choke plate for both cylinders that I can visually verify but when I start the bike I can hear one side kind of opening and closing as it makes a rattling sound. I can reach to the back and hold it with my fingers and the bike starts otherwise it just rattles and does not start. at all. I do not believe this has anything to do with the single cylinder idling as choke was like this even when the bike was running fine.
Any suggestion is appreciated.

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