XJ700XS Revival Project - Phase 2

Recall, I posted earlier the fact that I was given a '86 XJ700XS that hadn't run in at least a year. Here is what I have done thus far to bring her back to life. Shout out to bill for all his help as well.

After pulling the carbs and giving them a quick cleaning (didn't completely tear them down, but made sure there wasn't any visible debris and cleaned the jets), installed a fuel filter, new plugs, I have a running bike, but #4 cylinder is dead. Here are the symptoms and what I have done to diagnose.

It starts well cold, with choke, and all 4 cylinders are firing. Sometime after taken off the choke #4 cuts out, but it still idles pretty smooth. I actually thought it was running fine until I checked the exhaust pipes and found 1-3 blazing hot and 4 warm. I have eliminated electrical as an issue. I switched plugs and wires/caps with #1. #1 kept on firing and #4 remained dead. I figure that eliminates coils, plugs, wires, and caps. I took the vacuum cap off #4 and gave it a quick (very quick) squirt of carb cleaner. #4 picked right up and then immediately died. So I am guessing an fuel/air mixture problem.

I messed with the pilot air screw some, but it really didn't do anything when I screwed in or out. It was set at about 3 turns out, which seems to coincide with recommendations I have seen posted. I haven't messed with the sync screws.

The idle was pretty low (~750 rpm), probably because of #4. I turned it up some to 1000 rpm, but no change to #4.

I suspose I will need to pull the carbs again, but what should I be looking for? Any suggestions? What else could it be other than air/fuel? Bill, I know you have been thinking on this. Any suggestions, bring 'em on.