The new MS 251 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 fuel consumption is up to 20% lower compared to a STIHL 2-stroke engine of the same power output without 2-MIX technology.
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.
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.
Intense vibration at the handles of power tools can lead to long-term effects on blood vessels in the hands and arms. STIHL has therefore developed an effective anti-vibration system whereby the oscillations from the machine’s engine are dampened which significantly reduces vibrations at the handles.
Tool free filler caps
Special catches on the fuel and oil tanks for easy opening and locking without the need for tools.
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.
Ematic chain lubrication system
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 by up to 50%.
Side chain tensioner
The tensioning screw can be found on the side of the 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.
The HD2 filter is made from polyethylene filter material with up to 70% finer pores than fleece and polyamide filters to trap even very fine dust. In addition, it is oil and water-repellent and thus very easy to clean. The PET-covered filter cartridge with quick-release lock enables the filter to be assembled and disassembled in next to no time, without using tools. STIHL ElastoStartZoom
STIHL ElastoStart reduces the shock caused by the compression of the engine during starting. The compression shock is taken away from the user’s joints and muscles through a spring or rubber element in the starter handle.
Saw chain pitch .325″
Displacement cm³ 45.6
Weight kg 1) 4.9
Power-to-weight ratio kg/kW 2.2
Power output kW/bhp 2.2/3.0
Vibration levels left/right m/s² 2) 3.9/3.9
STIHL Oilomatic saw chain pitch/type .325″ Rapid Micro (RM)
Sound power level dB(A) 3) 113.0
Sound pressure level dB(A) 4) 103.0