Jonsered 450 won’t accelerate smoothly

[aljewett]

Good day all. My neighbour asked me to take a look at his J450 for him. New carb kit, ultrasonic cleaned, general clean up, new fuel filter. Got it running but it won’t accelerate if I gun the throttle. It bogs down like there’s an air leak somewhere.
Suspecting the intake boot, I got it off (miserable wire clip holding it on) cleaned it up and used some Motoseal gasket goo to give it a good seal. Also used a little where the carb mates onto the boot. Same problem. If I bring the power on gradually I can get it screaming pretty good. Gun it, and it bogs down. This is very much like a problem that I had with a different saw a while ago; torn intake boot.
Any thoughts on this would be appreciated.
Stumped in

 

[J D]

Have you actually tuned it?
If you can't tune it reasonably then either vac/pressure test it or try spraying carb cleaner around any potential air leaks while it's running