Idle adjustment Stihl 180

[bang]

I bought an am carb for it after a kit and ultrasonic clean didn't fix the original. The carbs have only an idle adjustment. The saw runs great but idles too high and the chain spins a little regardless of where set. Is the screw for an idle circuit and is there anything that can be done to idle down?

 

[Stihldoc]

The MS 180 saws have a Zama BIS (balanced idle system) carburetor. The idle speed is controlled by the “LD” adjustment screw that is an air bleed. It is not a traditional idle speed screw that opens the throttle plate, but bleeds air into the venturi. Don’t overthink this, it’s a really simple system that just works well. Not high performance, not a fine-tunable carb... just a simple carb for a basic saw.
If your saw won’t idle down by turning the LD screw counterclockwise, it probably has an air leak. A pressure and vacuum test will confirm or deny this problem. If it has an air leak, fix it. The 180 saws (1130 series) aren’t problematic at all, and are a dependable platform. One common issue is the plastic ring seal between the carb and the intake manifold. I’ve seen more than a few of them installed cockeyed and leaking air.
The 180 is a great little saw with few problems. Take the time to accurately diagnose this problem and keep it running for years to come.

 

[Chainsaw Jim]

The metering lever is likely set to high. Lower it to the correct setting and it should respond correctly.
The brand new out of the box OEM carb I installed on an ms180 the other day was set far too low from the factory and needed adjusted.

 

[a. palmer jr.]

I usually put the Walbro adjustable carburetor on in place of the Zama. Kinda hard to adjust unless your saw has the adjustment holes but it can be done with enough patience..

 

[C George]

I agree that the 180 is a very good little saw but with a few upgrades and tuning can be a great little saw. I have one that Im running a 211 18" bar and chain on and its powers it just fine.
Basically it just needs to be uncorked to run properly.

 

[C George]

I truely believe that many of Stihls products are highly restricted on the intake side and yes they would run 10-15 years that way . Any time you uncork a factory set up , your always flirting with a shorter life. Why all my equip see's only 32:1 fuel mix