MS 661 Petrol Chainsaw

Purpose-built for full-time forestry, the MS 661 C-M brings STIHL’s biggest 2-MIX powerplant together with M-Tronic 3.0 electronic injection: sensors read air-pressure, engine temp and load hundreds of times per second, so the saw fires up easily, reaches peak 5.4 kW output in milliseconds and never needs manual carburettor adjustment. A lightweight magnesium piston and compact crankcase help keep the power-head down to 7.4 kg while still driving 3.8 Nm of torque, giving loggers an exceptional 1.37 kg/kW power-to-weight ratio for faster felling with less fatigue.

Key features

• 91.1 cm³ 2-MIX engine (5.4 kW / 7.2 bhp) – 20% lower fuel use and 50% fewer emissions than pre-stratified designs.
• M-Tronic 3.0 – auto-tunes fuel and ignition for altitude, temperature and fuel quality.
• HD2 fleece filter + pre-separation – traps dust to 0.5 μm and multiplies cleaning intervals by five.
• Adjustable oil-pump & Ematic groove – lets you halve oil flow on short bars, saving up to 50% lubricant.
• Five-spring anti-vibration chassis – handles register 6.9 / 5.6 m/s² (L/R) to cut HAV exposure.

Technical highlights

Why it dominates big-timber work

With fuel-injected-like throttle response, a long-life HD2 filter that shrugs off redwood dust and a lightweight Light 04 cutting system that speeds every bore cut, the MS 661 C-M lets professional crews drop, buck and ring out giant hardwoods faster while burning less fuel and changing filters and chains less often.