STIHL MS 391

Pre-separation air filtration system

STIHL long-life air filtration systems with pre-separation achieve perceptibly longer filter life compared with conventional filter systems. Air drawn in is swirled. The larger, heavier particles are ejected. The pre-cleaned air is routed to the air filter via the pre-separator duct.

STIHL anti-vibration system

Precisely calculated buffer zones minimise the transfer of engine and saw chain vibrations to the front and rear handles. The chainsaw therefore runs noticeably smoother. This allows the user to save their strength and work longer.

Reduced-emission engine technology

2-stroke engine with stratified charge. A fuel-free layer of air is created between the burned charge in the combustion chamber and the fresh charge in the crankcase, reducing the amount of fuel lost during the charge cycle. This results in more power with a lower weight, up to 20% lower fuel consumption than regular 2-stroke engines and significantly reduced exhaust emissions.

Advanced combustion technology

Four overflow channels swirl the fuel-air mix before ignition, allowing for optimum combustion and highly efficient performance. The result is lower fuel consumption and high torque across a broad rpm range.

Tool free fuel caps

Special caps to open and close the tank cap quickly, easily and without tools.

Decompression valve

The decompression valve is part of the easy starting system. The valve should be pressed before starting to reduce the compression pressure when starting, as well as the effort needed to pull the starter rope. The decompression valve is semi-automatic; it must be pressed manually before starting, but then closes automatically.

STIHL Ematic System

Compared to conventional bars without Ematic, the STIHL Ematic system reduces the consumption of chain lubricant by up to 50 %, depending on the type of wood and the cutting attachment used. This system comprises a STIHL Ematic or Ematic S guide bar, a STIHL Oilomatic saw chain and a variable-flow or reduced-flow oil pump. As a result, virtually every drop of chain lubricant is delivered to exactly the right spot.

Side-mounted chain tensioning

The tensioning screw can be found on the side of chain saw through the sprocket cover. This removes the need for contact with the sharp saw chain.

Single-lever master control

All important functions such as start, choke, throttle and stop are operated via a single lever.