16/18/20" Bar Suppllied - 64.1CC Engine - 4.5 Horsepower
STIHL engine technology means low fuel consumption, longer run times and reduced emissions in this high-powered chain saw. The MS 391 features our newest engine technology that adds fuel efficiency while reducing emissions as compared to other models. Though equal in weight, the MS 391 is more powerful than the MS 311. Add to that an optimal power-to-weight ratio and you have a chain saw that’s cut out for the big jobs in field, farm and ranch. Felling trees, cutting firewood and cleanup after the storm just got a whole lot easier with the rugged MS 391.
Reduced-Emission Engine Technology - Caring for Nature
The STIHL Inc. “Caring for Nature” seal identifies its powered products that are more environmentally conscious, producing zero or low exhaust emissions. STIHL Inc. defines “low exhaust emissions” as being cleaner than EPA and/or CARB exhaust emission standards.
STIHL has developed a system for minimizing the vibration levels of handheld outdoor power equipment. The STIHL anti-vibration system helps reduce operator fatigue and provides a more comfortable working experience.
The decompression valve, also referred to as 'deco' or 'deco valve', vents compression in the cylinder for easier starting. The decompression valve temporarily reduces the compression in the combustion chamber during cranking and helps reduce the effort needed to pull the starter rope. It is opened manually and closes automatically as soon as the engine fires.
IntelliCarb™ Compensating Carburetor
The IntelliCarb™ Compensating Carburetor is designed to automatically adjust the air/fuel ratio when the air filter becomes restricted or partially clogged and maintains the engine’s correct RPM. IntelliCarb™ uses air from the clean side of the air filter to control the diaphragm and flow of fuel. As the air filter becomes dirty and less air is available for the carburetor, the IntelliCarb™ system adjusts the fuel flow to compensate for the decrease in air flow. This is in contrast to typical carburetors that utilize this air from the “dirty” side of the air box.
Ematic™ Lubrication System
The Ematic™ guide bar when used with STIHL OILOMATIC® saw chain will provide proper lubrication and less oil consumption than conventional methods. The system works because two ramps, strategically placed in the guide bar rail, help contain the flow of oil and direct all lubrication to the sliding faces of the bar and chain links as well as the rivets and driver holes, which in turn can reduce bar oil consumption up to 50%.
Master Control Lever™
The Master Control Lever™ is an easy to use single lever, operating the choke, starting throttle lock and on-off switch. The operator must pull the throttle trigger before moving the Master Control Lever™ to the choke position.