FS240 driving me nuts with off idle bog.

[ANewSawyer]

I bought a new FS240. Starts easy, runs fine at part or full throttle but has a terrible of idle bog, specfically with a blade. Is that normal? It does it when hot or cold.. When it is all the way back at idle, I pull the throttle rrrrrrrrrrRRRRRREEEEEEEEE! It actually has to spin up. Am I just spoiled by my 525LS and super running saws to not expect spool up? I have got the carb adjusted as correctly as I know how. I have tried seating the L needle (acidently) and making it so rich it dies out at idle. Been using it all spring and summer anyway. I like it except for that.

 

[sawfun]

Maybe a low side adjustment if it's not Mtronic? Neither neither the fs550 I had or music fs250 have any bog or hesitation.

 

[ANewSawyer]

I have tried that. Accidently seated the L needle once and had it so rich it died at idle. Gave it a muffler mod a week or two ago. Runs really strong on the high end but still has that bog. Hmmm.

 

[Ktoom]

What style/type is the carb? Just wondering if its the same style as whats on the fs94?

 

[ANewSawyer]

I don't know offhand but I can find out!

 

[sawfun]

Seating the needle should make it leaner, opening it up should riches it, which is what it sounds like it needs, especially after a muffler mod.

 

[backhoelover]

have you check the nozzle check valve could be leaking by. might also want to do a pressure and vac test

 

[backhoelover]

H: Open 1 1/2 turns Low speed screw L: Open 1 1/4 turns Special servicing tool Screwdriver 5910 890 2307

has a new style wtf carb

 

[backhoelover]

the ref about is just a starting point. can you get a pic of you plug.

 

[backhoelover]

how long have you had the unit. they did a complete overhaul on the unit not to me years back. changed the whole engine just about

 

[backhoelover]

new duhhhhhh

 

[backhoelover]

new carb for that thing is 130.00

 

[backhoelover]

well that sucks you cant but just a nozzle check valve. here is what i would do.
there is a #0.41 fixed jet in carb. i would order a 0.42 and thow it in there. i have had the wya twin barrels have a bog off idle i went up on the next size jet and it has worked everytime knock on wood

 

[ANewSawyer]

Bought unit new this spring. The dealership has only been open about a 1 and 1/2 years. They had to order it and it came with a new style gearbox that non of the old three bolt guards mount to. It is a four bolt guard. I believe that there is a low side bypass because the unit kept idling when I seated the needle. This should be a simple tune change it is not. I have messed with that needle to the point of disgust.

Facts:
The bog is not nearly as bad with a string head on it. Still there but small.
I retuned after the muff mod. Turned the needles with the unit off. Four stroked when running so I leaned it out a touch. Still bogs.
It has about four tanks through it.

Harley, thanks for the factory settings. That is just a starting point but will help. I have more I am trying to think of but can't.

 

[ANewSawyer]

Seating the needle should make it leaner, opening it up should riches it, which is what it sounds like it needs, especially after a muffler mod.

I did richen the carb. I had held out slight hope the muffler mod would help, it did, just not how I needed.

H: Open 1 1/2 turns Low speed screw L: Open 1 1/4 turns Special servicing tool Screwdriver 5910 890 2307

has a new style wtf carb

wtf carb, are you serious? I have the tool now, thanks to that pack of the tools you pointed me to. I have been doing it with a piece of aluminum tube turned by screwdriver. Ugly but does work.

 

[backhoelover]

yes

 

[backhoelover]

cause it makes you got wtf when your working on them or wanting parts lol. been look for a carb kit for months lol. trying not ot pay 12.99 dealer price lol

 

[backhoelover]

if it is still idling when you close the l needle then you have a leaking idle welch plug

 

[ANewSawyer]

Great. It is a Zama carb ain't it.

 

[backhoelover]

nope walbro