[Katchup]

Any updates on your issue? I have an '89 Kat 600 experiencing what sounds to be an identical problem. My Cyl#4 gets warm, not hot, and not cold. The plug is dry, black, and sooty. There’s lots more I could describe and I’ve gone through the same troubleshooting list you have. I just can’t nail it down. I’ll wait a bit to see if you have news before I start a thread of my own.

[ChandlerW]

No updates. Same problem. The cold cylinder moves around too. Once I get #4 working then #2 will go out, get that working and #3 will drop out. Get #3 working and #1 will stop. Not in that order.
It's a mess.
I'm thinking that my float o-rings are not seated right in the holes. I have a picture of that in My Garage to show what I think the problem is.

[III]

I'm no expert, have been learning from these guys and working on mine as well. May be a silly questions, but has the picture with the carbs on the bike, with the floats up been rotated or turned upside down? If so, nevermind. If that picture is right, looks like the carbs are on upside down.

[ChandlerW]

Yeah I put the carbs upside down to take the picture and also measure the float distance. I'm going to try a suggestion someone gave me when I get home from doing mall duty today.

They are clean as a whistle too.

[steves]

No updates. Same problem. The cold cylinder moves around too. Once I get #4 working then #2 will go out, get that working and #3 will drop out. Get #3 working and #1 will stop. Not in that order.
It's a mess.
I'm thinking that my float o-rings are not seated right in the holes. I have a picture of that in My Garage to show what I think the problem is.

Vac leak. Check the intake boots on the motor.