New plunger black plugs

Hello everyone, I tried my bike with new plugs(b8es), new plunger, carb freshly Synchronized and I stil have 3 black plugs (1-2-3) the last cylinder(4) is almost perfect. Some bug like before in 3-4000 rpm!!??  I tried to put the air screw on my Vm28ss at 2 turn for the 1-2-3 cylinders and the other one is still 1 1/2 turn out !! What do you think ?
thank youu

Wet or dry black?
Black plugs can be caused by several things but knowing if wet and sooty or dry and sooty narrows it down. 
​​​​​​What bike is it? B7ES run hotter and cleaner. 
Don't use a plug with a R in the code. 
 

Float levels correct?

Good Ridin'
slmjim & Z1BEBE

Float level all set at 3mm with clear tube. And they are black sooty. Bike is surging 3-4000rpm the left one is one of the three that are black like that!! The screw on the Pod filter side, is it a Air screw right? More turns out; more air?

That looks dry sooty which means those three are running far too rich.
3 - 4k rpm is when the needle jet also becomes active along with the pilot jet. 
Possible causes are, 
Fuel height in bowl too high. 
Weak spark caused by bad coil, low voltage to coil, dirty connections in the ht lines or too high resistance in the caps/plugs. 
Incorrect or Incorrectly set jet needle and/or worn needle jets. 
Choke plunger seals are totally shot and letting fuel by. 
Low compression on affected cylinders. 
Thats assuming that the brass carb parts haven't been swopped out using crap ebay repair kits.
ONLY EVER use genuine mikuni or Keyster jets and needles etc and ensure only one component in the ignition line has resistance or better still no resistance. 
 

The jets are mikuni one, new engine 150psi on all 4, new plungers, 3mm fuel level all set, valves clearance, carb are set mechanically with 1/8 drill bit.. needles are one notch down I guess (dyno guy has play with it!) 

The coils have 2.3 to 2.6 ohm

I'd start with checking what the dyno guy has said. 
Needles, assuming they are stock should be 4th slot from the top.
I.E. second up from the bottom. 
Exactly which plugs do you have fitted?
What voltage are the coils getting? 

I haven’t checked the voltage(oem coils), the wire are 7mm with no resistcap (ngk) . The dyno guy says thats nothing to do..  I run b8es 

Needle clip slot position has everything to do with how the mid range fuel supply is delivered!
Take what you want from what he says but I've over 50 years experience with these carbs. 
Dyno testing and tuning is about setting the whole package to perform at its optimum which begs the question why did he give back set up so wrong? Give back to him to sort. 

 

Perhaps helpful? What version of the VM26SS's do you have? If you have the 76 KZ900 1200's they had unique needle jets and jet holders. Photo shows to the left the correct components for the 76. The 1977 KZ1000 had a different combination. KZ900 had a 243 series O-6 and KZ1000 Had a 258 series O-6. KZ900 had NO oring on jet holder, KZ1000 did. Don't know if you'd cobbled-up bits to make a set or not?? And a handy tool that fancy AF Dyno won't tell you is each individual cylinders A/F at the sweet spot your lacking in real time per cylinder, not as a whole which adds to the confusion.    

Warren3200gt wrote:

Needles, assuming they are stock should be 4th slot from the top.


 

Carbs are Z1000 VM28 so should be 3rd ( middle ) groove as stock.

Considering that the 3 sooty plugs are the same i'd be looking at the leaner carb first as the odd one out to see if the fault lies there with an air leak etc and then address the mixture once all the plugs read similar.
If the mixture can't be leaned sufficiently on the air screws ( max 2.5 turns out ) it's likely that the pilot jets need reducing if in fact it is only the idle mix that is affected and the rich condition is not present following a high speed plug chop..