Im kindve lost

1985 zx550. It has tk26 carbs on it (second model without the plug) and stock airbox. 

Backround: Bike sat in a shed in parts before I got it for a long time. Restored most of it at this point. 

Problem: A few weeks ago I started the bike after the carbs latest cleaning. It was a little hard starting but would start. Idled fine but the throttle response was very delayed and would hang. The throttle response was good when revving after the rpm’s were up. Now today I went to start it up today and it wouldn’t start on its own. It would only start on starting fluid and die when that ran its course. 

What I’ve done:
-checked coils (resistances). Good.
-reshimmed valves to proper tolerances. 
-plugs cleaned and gapped
-carbs went through so many times
    -all jets are to spec of manual
    -pilot screw turned out to stock suggestion (two turns) 
    -checked vacuum with gauge. 3/4 are the     same but one won’t adjust regardless of turning butterfly screw in or out. Butterfly valves all look fine. 
   -fuel level set via wet method with clear bowls I 3D printed to 7mm as per spec 
  -brand new intake boots 
​​​​​​  - tried spraying around intakes to see if rpm’s would rise but no noticeable difference
  - cleaned every port of every carb in the set with very small wires, carb cleaner, and compressed air. Compressed out comes out great of each port. 
   - each jet cleaned until a clean circle of light can be seen through. 
   - slide diaphragms don’t have any tears. When lifted each falls the same (slowly).

I’m not sure where to go from here. Everyone keeps saying clean but I don’t know if I can clean anymore. I’ve rebuilt these gpzs before and so this isn’t my first time with these carbs but I’m at a loss. A bit embarrassed to say I’m a mechanical engineer lol. Any ideas? 
 

Certainly sounds like an air leak if you can’t adjust the vacuum - are the vacuum caps on the carbs sealed? Have you tried setting the petcock to prime and clamping the vacuum pipe?

Sorry, left that part out. The vacuum ports are capped. And I’m using a small auxiliary tank until it’s running right.

Fuel, compression, ignition, thats all you need.
Check compression with gauge.
Lay one plug on engine while it runs and watch for spark in dark garage or night.
You have to isolate which of the three is missing.
 

Each cylinder has around 130psi. Each plug is sparking with a spark checker that has been verified on an operational vehicle I have. Again ive rebuilt bikes (same model in the past). This one is particularly giving me a hard time. 

It’s fuel delivery. I’m just at a loss as to what to try on the carbs next. I’ve torn them down completely several times. Cleaned them over and again. Made sure good flow in each passage. Each jet has a clean uniform hole. All jets and settings are set to factory. I’m trying to figure out what I’m missing or where I’m going wrong. 

In reading your posts I did not notice if there was any mention of air filter(s). Are you running stock filter/air box or pods or none while attempting to solve the issue?

gd4now wrote:

In reading your posts I did not notice if there was any mention of air filter(s). Are you running stock filter/air box or pods or none while attempting to solve the issue?

First post says stock air box.

Carb holders could be old and leaky, or the carbs may not be fully seated in the holders.

Are the float bowl vents clear - you need atmospheric pressure in the float bowls for fuel to be drawn up by the manifold depression

That just shows how much I am paying attention. Sorry about that, no real excuse.