Choke or lack of it

Hi guys popped out today for a quick ride, however she wouldn’t start very well as mentioned on my other post for some strange reason the choke / enricher doesn’t seem to function as it did before. Normally I start her on choke and she screams her nuts off I lower the choke and she settles down then after a minute the rev’s pick-up again and I have to close it down some more. Now she runs perfect plugs are great and no misfire etc, but operating the choke from cold only raises the tick over very slightly? I can ride her away but it’s taking many goes to get her to actually startup ?
Pilots are 1 size up and I found 3 out of the 4 gaskets between the headers and balance pipe were missing, the electronic ignition seems spot on.
Why have I lost the chokes operation ? I cannot believe all 4 plungers have failed ?
 

Assuming vm carbs?
Are the lifters loose on the shaft and not lifting the plungers completely? 
Are the lifter forks bent downwards and not lifting the plungers completely?
Have you had the carbs off for cleaning and you've refitted the lifters upside down? 
The lifters are soft metal and it doesn't take much to bend the arms. 

Choke pickup tube, which draws fuel from the float valve and transports it to choke plunger cavity could be plugged up.

And/or, the passage in the float bowl, into which the choke pickup tube resides, could be plugged.

Both of these passage blocks are quite common.

 Carbs have been off several times and are spotless inside the plungers again all move freely, I wouldn’t be wasting your time without checking the obvious. I just cannot understand what’s changed to affect all 4 cylinders ? It’s as if the supply to the enrichers is blocked but they are not?
I’ll have another look tomorrow morning but what am I looking for lol



 

Why did you increase your pilot jets?  How many turns out are your pilot air screws?

The bike was taking 10 minutes to warm up before I could ride her without either her bogging down or needing choke, it stated somewhere the US bikes were set lean for emissions and someone mentioned increasing the pilot jets to improve it; hence I went 1 size bigger. Since then I have resolved a few other problems and she runs great now.
The pilot screws were to far out, I might have been thinking about my KH400 when setting there...1-3/4 out lol....time will tell the workshop book says 3/4 + or - 1/8 turn.
 

Got the 3/4 turn from here ?
 

3/4 out is correct for Fuel screws, under the bowl cylinder side of the slide. Part 6 in your diagram. 
1 3/8 out is correct for Airscrews on the carb side airbox inlet side of the slide. 
No16 on your pic is an airscrew or a plug not a fuel screw.
VM carbs came with either fuel screws, air screws or both. Which do you have? 

Here are mine
 

You have pilot airscrew carbs. Those should be set at 1 & 3/8 out from lightly seated. Then once the engine is warm colour tuned for best mixture.
"IF" you have those set at 3/8 out then you have a rich pilot mixture. Add choke to that and it's probably too rich to fire giving the impression you choke isn't working. 
Additionally you have the vac tap pipe open. This must be plugged unless it's connected to the fuel tap or it'll just draw air into carb 2  and no fuel will be drawn through the pilot circuit as there will be no vacuum in the carb throat. 
 
​​​​​​Set them to 1 3/8 out. 
With a cold engine use full choke, absolutely NO throttle input, hit the start button and it should fire and rev high at about 3.5k. Feather the choke closed until it's running at about 1.8 - 2k rpm. After about 30 seconds you should be able to shut the choke completely. 

Vacuum pipe was only open as tank was off, I know what you mean about running with it open; number 2 just doesn’t work lol.
I’ve got the next size up pilots fitted 17’s if the 1-3/8 out doesn’t cure the choke and starting problems would this suggest dripping back to the original 15’s ?
I really appreciate the info and advice I don’t mind pulling the carbs again if needed .
 

Your running stock airbox so pilots should be 15. Mains should be 102.5. Needle should be slot 4 from the top.
Your testing with open carbs not drawing air through the air box. It'll run slightly weak but it won't stop it running.
Where are you in the UK? I'm by Brands Hatch Kent. Get lots of local zeds brought to me to sort out.