Low rough idle speed , back firing when slowing down or gearing down runs great at higher speeds and idles after it warms up but idle speed is very low. thank you

Typical for any carburetor is 1 1/4 to 1 1/2 turns (out). These are just rough settings to get the saw running. Remove chain, turn idle throttle speed screw in to increase idle rpms so its less likely to stall. Follow mfg instructions for starting.

Once running, adjust low speed mix and allow a couple minutes to warm. Then re-adjust low speed and lower idle rpms by turning out idle throttle speed screw. Then with throttle wide open adjust high speed mix. If saw hesitates from idle to full throttle, open low speed mix 1/8 turn and readjust high speed mix.

If saw doesn't fire in 3 or 4 pulls remove plug. If plug is dry no fuel, if wet either no spark or idle mix to rich (or fuel metering may be fouled).

Here are the most common causes of idle surge, rough idle esp when cold and stalls at stops, slow idle speed, erratic idle speed, rough idle and engine hesitation (and other problems), it is in most cases the idle speed control air-bypass valve and or throttle valve and upper intake, these area's get full of gunk and combustion residue over the miles and cause idle issues (stalls, low idle) like yours, Get a can of intake cleaner from any local parts store, not carb spray, intake cleaner, it is made by a company called CRC, remove the air intake hose to the engine, hold the idle high so the engine won't stall, then spray the can of cleaner into the intake while keeping the engine running, use at least 1/2 the can, shut down the engine and disconnect the battery for 5 minutes, then restart and complete a number of mixed driving cycles, town, freeway, stop and go etc., after a few days the problem will go away as the system will relearn to the clean intake.

Could be a vac leak, or a dirty throttle body, or a faulty idle air control valve. The computer controls idle speed by regulating the amount of air into the intake. Could also be something pulling on the throttle cable such as the cruise control.

For this types of problem,there are few help inks to troubleshoot the problem.Click the link below to go through the troubleshooting procedure to resolve the issues :----Idles rough and quits when gas pedal is pressed less? http://technoanswers.blogspot.in/2012/01/1999-ford-f-150-idles-rough-and-quits.html-----------van idles rough? http://howtobyme.blogspot.in/2012/01/2004-ford-freestar-van-idles-rough.html
--------------runs lean and idles rough? http://technoanswers.blogspot.in/2012/02/ford-runs-lean-and-idles-rough.html
-----------Car still runs Rough after tune up? http://howtobyme.blogspot.com/2011/12/car-still-runs-rough-after-tune-up.html
------------Idle flair is noticed on car? Rough idle? car will not idle? Erratic idle speed? http://technoanswers.blogspot.in/2012/02/idle-flair-is-noticed-on-car-rough-idle.html
----------High rpm in neutral? Inconsistant high RPM in neutral? http://technoanswers.blogspot.in/2012/02/high-rpm-in-neutral-inconsistant-high.html
------------Engine Backfires? http://technoanswers.blogspot.in/2012/02/jeep-backfires.html----------- Nissan stalls and bucks on Acceleration?

http://technoanswers.blogspot.in/2012/02/nissan-pathfinder-stalls-and-bucks-on.html

-----------
Nissan Pathfinder Backfires? http://technoanswers.blogspot.in/2012/02/nissan-pathfinder-backfires.html
---------How to adjust rpm? http://schematicsdiagram.blogspot.com/2011/12/how-to-adjust-rpm-on-2009-dodge-charger.html
------------Engine cuts out at 3000 RPM? http://schematicsdiagram.blogspot.com/2011/12/engine-cuts-out-at-3000-rpm.html
----------This will help.Thanks.

why do you want your rpms higher while idling? you don't want them high because your gas bill will reflect that. slow shouldn't matter but if it's dying while on idle it could either be your mass air flow sensor or your fuel filter being clogged

Probably a bad idle air motor, it controls idle electronicaly

probable vacuum leak query brake booster

My name is Dennis and I also have the model you are having difficulty with and I can only repeat the instructions from the owners manual (with personal comments) because they have always served me adequately I hope that will serve your needs.
IDLE ADJUSTMENTS:
There are three adjustment screws on the carburetor labeled
H (for High speed MIXTURE)
L (for low speed MIXTURE)
T (for idle SPEED SETTING)
They are located just above the primer bulb. If your saw floods so soon in the starting process the idle mixture setting can be set too rich and the speed may be set too slow. Remember the chain will not move when the idle speed is set correctly with a WARM ENGINE!
Adjust the idle speed to just below chain movement WITH A WARM ENGINE this is just below the activation RPM of the centrifugal clutch. Let the engine run at a higher speed than idle until it is warm -- 3 min -- you may have to keep goosing it until then.
Please don't exceed the limits of the plastic limiters when making adjustments.
If you haven't adjusted the mixture screws you may just have to adjust the idle speed and that can start my turning that screw all the way in to the stop and then back out 4-1/2 turns for a good place to start. FAST IDLE -- Adjust the speed until the engine runs with out the chain moving. Adjust clockwise to increase speed. C clockwise to decrease engine speed.
Accelerate the engine and if it stumbles and makes too much smoke it's too rich turn the
LOW SPEED MIXTURE (in) clockwise in 1/16 a turn increments NO MORE at a time because a two cycle needs to run at a setting for a short time to really prove the setting. don’t run it wide open to warm it up but it should be at a fast idle. Nothing you do will be proven correct until the engine is warm.
Good Luck
Glad to be of assistance - please rate the solution because I will learn from your rating. Thank you

Hi Guest,
My name is Dennis and I also have the model you are having difficulty with and I can only repeat the instructions from the owners manual (with personal comments) because they have always served me adequately I hope that will serve your needs.
IDLE ADJUSTMENTS:
There are three adjustment screws on the carburetor labeled
H (for High speed MIXTURE)
L (for low speed MIXTURE)
T (for idle SPEED SETTING)
They are located just above the primer bulb. If your saw floods so soon in the starting process the idle mixture setting can be set too rich and the speed may be set too slow. Remember the chain will not move when the idle speed is set correctly with a WARM ENGINE!
Adjust the idle speed to just below chain movement WITH A WARM ENGINE this is just below the activation RPM of the centrifugal clutch. Let the engine run at a higher speed than idle until it is warm -- 3 min -- you may have to keep goosing it until then.
Please don't exceed the limits of the plastic limiters when making adjustments.
If you haven't adjusted the mixture screws you may just have to adjust the idle speed and that can start my turning that screw all the way in to the stop and then back out 4-1/2 turns for a good place to start. FAST IDLE -- Adjust the speed until the engine runs with out the chain moveing. Adjust clockwise to increase speed. Cclockwise to decrease engine speed.
Accelerate the engine and if it stumbles and makes too much smoke it's too rich turn the LOW SPEED MIXTURE (in) clockwist in 1/16 a turn incriments NO MORE at a time because a twocycle needs to run at a setting foe a short time to realy prove the setting. dont run it wide open to warm it up but it should be at a fast idle. Nothing you do will be proven correct untill the engine is warm.
Good Luck
Glad to be of assistance - please rate the solution because I will learn from your rating. Thank you
Your IDLE MIXTURE may be too rich causing the engine to flood.

Hi 1tgriffin,
My name is Dennis and I hope that will serve your needs.
IDLE ADJUSTMENTS:
There are three adjustment screws on the carburetor labeled
H (for High speed MIXTURE)
L (for low speed MIXTURE)
T (for idle SPEED SETTING)
They are located just above the primer bulb. If your saw floods so soon in the starting process the idle mixture setting can be set too rich and the speed may be set too slow. Remember the chain will not move when the idle speed is set correctly with a WARM ENGINE!
Adjust the idle speed to just below chain movement WITH A WARM ENGINE this is just below the activation RPM of the centrifugal clutch. Let the engine run at a higher speed than idle until it is warm -- 3 min -- you may have to keep goosing it until then.
Please don't exceed the limits of the plastic limiters when making adjustments.
If you haven't adjusted the mixture screws you may just have to adjust the idle speed and that can start my turning that screw all the way in to the stop and then back out 4-1/2 turns for a good place to start. FAST IDLE -- Adjust the speed until the engine runs with out the chain moving. Adjust clockwise to increase speed. C clockwise to decrease engine speed.
Accelerate the engine and if it stumbles and makes too much smoke it's too rich turn the
LOW SPEED MIXTURE (in) clockwise in 1/16 a turn increments NO MORE at a time because a two cycle needs to run at a setting for a short time to really prove the setting. don’t run it wide open to warm it up but it should be at a fast idle. Nothing you do will be proven correct until the engine is warm.
Good Luck
Glad to be of assistance - please rate the solution because I will learn from your rating. Thank you