why why why - weird adjustment screw behavior

I feel this topic is under the big word "HELP"

My carbs were rebuilt - worst mistake of my life. Why I didn't just leave them alone or at least do the job myself, because now I have to anyway.

The "professional" stripped the 3rd carb butterfly adjustment screw thread in the body of the carb. Did tell me it "is a bit worn - but should be fine"!

Yes - well useless is the reality - so I bought a new body on ebay whilst the bike was at his shop and said - here fix it.

So now in the end after he said Its pretty good - I found it still had three issues and did them:-

1. Reset all the float levels to correct specs.
2. Bought a new 3rd carb adjustment "screw" (he left a stripped screw in there too.)
3. Attempted to calibrate the carbs to No2 carb - and this is the reason for this thread

Carbs 1 + 4 adjusted perfectly into place to match Carb No 2.

Carb 3 (as always) is the issue and its weird and the result is simple but i cannot figure out why -and how to fix it. The carb adjustment screw easily adjusts the carb to sync equal to No 2 carb BUT - it ALSO adjusts the idle speed - so either you get a correct setting of butterfly AND 3000 RPM idle or

Correct idle speed and incorrect synch reading by large margin of 20.?????

So - given the synch screws are not supposed to alter idle or idle is not supposed to change butterfly positions - why are they connected.

A good motorcycle mechanic mate of mine who lives 500 miles away (so cant help) suggests maybe the 'professional' assembled the carb incorrectly when replacing the 3rd carb. Fair ussumption - but how do I tell. ?

If anyone can assist or point to a clear drawing or better still clear viedeo on assembly of these carbs - I could at least check this out.

or

If thats not the issue - what might be. THere is NO vacuum leak. I have checked and even put new carb boots on since I had a set to just make sure of that.

I would really appreciate some learned knowledge here before I pull these thinks out yet again thanks.

Here's one of the several downloadable carb articles from kzr's file base:
Click here > kzrider.com/filebase/download/26-general...tor-rebuild-tutorial

And here's some more:
Click here > kzrider.com/component/jdownloads/search

Good Fortune!

Pictures of the carbs and model of bike would help a lot here but generally the idle adjustment screw should be separate and usually runs on the cable reel or the sync carb.
There must be something stopping the butterflies from closing completely ( throttle cables too tight etc ) if there is no idle screw.
If 2 is the sync carb then there must be idle adjustment there if not on the cable reel.
However if number 3 is governing the idle then why not use that as the sync carb and not 2 to get a better result as a last resort..

What bike and carbs?

Based on your comments about butterfly's I'll assume you have a later KZ with CV carbs. To sync those carbs there is typically adjusters between 2-3, 1-2, and 3-4. There is no independent adjustment that I'm aware of. And the idle speed adjust is independent of sync. If idle is too high after sync just set it lower using the idle adjustment stop screw.

Sorry Guys - when you live a restoration you forget only you kow the bike Its a 1982 KZ1100 Spectre.

Tks for the links too.

Rgds

GReg