STIHL MS391 Farm Boss® Chainsaw

The innovative long-life air filter system greatly extends the service life of the filter. Air routing removes larger particles of dirt, meaning the actual filter has less to do. So the saw can be used for longer without having to clean the filter.

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

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

This controller in the carburettor prevents the fuel-air mixture getting richer as the air filter becomes clogged. The correct quantity of fuel is delivered to the carburettor depending on the quantity of air passing through the air filter. This keeps the fuel/air ratio in the combustion mixture constant and hence also the engine power. The filter doesn't need to be cleaned until an appreciable drop in power occurs.

The exact chain oil output can be adjusted maunally for varying conditions, allowing for a reduction of up to 50%.

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

The tensioning screw is located on the side of the chain saw through the sprocket cover. Chain side tensioning allows the saw chain to be retensioned effortlessly, avoiding any contact with the sharp chain.

The Ematic chain lubrication system ensures pinpoint lubrication of the saw chain links and guide bar rails. When used with STIHL OILOMATIC saw chain, it will provide maximum lubrication, longer wear and less oil consumption than conventional methods of chain lubrication. The Ematic system can reduce bar oil consumption up to 50%.

Special caps on the fuel and oil tanks are designed for easy opening and locking without the need for tools.

STIHL ElastoStart reduces the shock caused by the compression of the engine during starting. The compression shock is taken away from the users joints and muscles through a spring or rubber element in the starter handle.