STIHL MS 391 High-Torque Gas Chainsaw 20-Inch (64cc)

The STIHL MS 391 is a high-torque 64cc farm and ranch saw built for firewood cutting, land clearing, and construction timber work where a homeowner-class saw runs out of power.

Torque built for tough wood

A 64cc STIHL 2-MIX engine and four-channel fuel delivery keep the 20-inch bar cutting through dense or larger-diameter logs without bogging down.

Easier starts under load

A manual decompression valve reduces cylinder pressure during starting, making it noticeably easier to pull-start even after the engine has been run hard.

Consistent power as filters load

A compensating carburetor automatically adjusts the air/fuel mixture as the air filter picks up dust, so cutting performance stays consistent between cleanings.

Less oil, less downtime

The STIHL Ematic lubrication system trims bar and chain oil consumption by roughly half compared to older designs, extending time between refills.

Key features

• 64cc STIHL 2-MIX engine, 4.5 hp
• 20-inch guide bar with 3/8-inch chain
• Manual decompression valve for easier starting
• Four-channel fuel delivery technology
• Ematic chain lubrication (up to 50% less oil use)
• Anti-vibration system
• Side-mounted, tool-free chain tensioning

Specifications

Frequently asked questions

What fuel mix does the MS 391 need?

Run it on a 50:1 mix of unleaded gasoline and STIHL two-stroke oil; using an incorrect ratio can damage the engine and void coverage.

Who is the MS 391 built for?

It's aimed at farmers, tradespeople, and landscapers cutting larger volumes of wood or bigger-diameter logs than a homeowner saw is designed to handle.

How does the decompression valve help?

It briefly releases cylinder pressure during starting, reducing the pull force needed to get the engine running, especially when the engine is already warm.

What size bar does it use?

This listing is configured with a 20-inch guide bar and matching 3/8-inch chain for larger cutting jobs.

What is in the box

The MS 391 ships with the powerhead, a 20-inch guide bar and chain installed, a bar scabbard, combination tool, and owner's manual.