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

 

[Old2stroke]

As mentioned, have you tried adjusting the carb? Usual problem with bogging off idle is the idle mix screw is set too lean or the transfer ports behind the throttle plate are plugged. If that carb has an accelerator pump, it can also be the problem.