MS 391

Standard

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  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.
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  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.
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  Controlled-delivery oil pump

  Different bar lengths, wood types and sawing techniques require different amounts of oil. The controlled-delivery oil pump allows the user to select just the right amount of oil for the job at hand.
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  Compensator

  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.
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  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 reducing 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.
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  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.
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  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.
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  Single-lever master control

  All important functions such as start, choke, throttle and stop are operated via a single lever.
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  Side-mounted chain tensioning

  Side-mounted chain tensioning makes it easy to tension the chain safely.
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  Tool free fuel caps

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