Stihl MS 251 Chainsaw 18"
The new MS251 is ideal for a variety of applications, from cutting firewood to timber construction. This high torque engine is easy to start and comfortable to use, with a high cutting performance. Emissions are cut by 70% and up to 20% lower fuel consumption compared to a STIHL 2-stroke engine of the same power output without 2-MIX technology.
STIHL M-Tronic (M)
For a cold start, the STIHL M-Tronic only needs one start position on the combi-lever. After starting, you can immediately power up to full speed. The amount of fuel required is precisely calculated by the system and supplied as needed. Otherwise, start in position I as usual.
Due to compression pressure, jerky stresses occur when starting internal combustion engines. The damping element in the ElastoStart special starter grip alternately absorbs and releases force according to the compression pattern. The result is smooth, even starting.
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.
This air filter keeps even the finest dust away from the engine, ensuring a particularly long service life. Thanks to its special material, the filter can easily be cleaned by washing, for example with STIHL Varioclean and warm water.
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.
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.
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 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.