Jonsered CS2147 (Husqvarna 346XP) Assistance Required

[Blade]

Hi Guys,
I have a customers Jonsered CS2147 (Husqvarna 346XP) that came in for a full strip-down and rebuild. New piston & cylinder, plus every seal, gasket, hose, intake boot, bearings etc were replaced (all genuine OEM parts). The Zama carby was also rebuilt. Once assembled, it was pressure tested to 8 bar and had no leaks whatsoever.
Nothing I haven't done hundreds of times before.....however, when I test run the saw it idles at about 3500rpm.
With the usual culprit being an air leak somewhere, I checked torque tensions, all the hoses, gaskets etc, and even swapped the carby and decompression valves.
I re-pressure tested and once again no leaks.
Start the saw, and once again it's running between 3400 and 3500rpm, with the idle adjustment screw doing absolutely nothing.
What am I missing here guys ???? Your thoughts, suggestions, and alike are most welcome as this saw is doing my head in

 

[BC WetCoast]

Try posting this in the chainsaw sub forum, you'll probably get a better answer. That's where all the saw builders hang out.

 

[Canker Mechanic]

Head gasket or seal on that saw comes to mind. Does or have the two piece rubber gasket on either side of the crank shaft?

 

[Canker Mechanic]

Just checking back.....that saw may have a silicone base gasket that is blown out. It may run but not well and there is no amount of adjustmen in the carb that will heal the that air leak.