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

 

[hacskaroly]

It bogs down like there’s an air leak somewhere.

Those can be tricky to ferret out. If you can get the saw running (idling), try spraying brake cleaner (non-flammable) around both oil seal areas, if there is an air leak at either one, it will suck in the brake cleaner and stop the saw (no damage). That will tell you if either seal is leaking. You can do the same around the intake boot/connection that you fixed, just in case there is still a leak around there. Not sure how probably, maybe the gasket under the cylinder is degrading and air is getting in there.

 

[Woodwackr]

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

Did you, perhaps, get some sealant into the impulse port?
Sounds like a fuel delivery problem

 

[heimannm]

Try adjusting the L screw on the carburetor. Start with 1/8-1/4 of a turn out (CCW) and go from there.

Mark