You may think that getting a chainsaw like the MS 391 that hails from a reputable brand will save you the stress of defects and low material quality, but there’s still a chance you can end up with a saw that lacks power and strength, making it incompatible with your needs.
To help you decide, I’ll thoroughly discuss the tool in this Stihl MS 391 review.
What I Like
- It has fewer exhaust emissions than other gas models
- The air filter cleaning process is efficient
- It has less vibration which results in more accurate results
- It has an auto-adjust fuel flow system
- The side chain tensioner is very accessible
What I Don't Like
- It's not the newest release of the brand
- Users may find limited aftermarket components
Design, Weight, and Build Quality
Since MS 391 is a gas chainsaw, it’s a no-brainer that it’s heavier than battery-operated models. It has a powerhead weight of around 13.67 lbs, perfectly matching the recommended guide bar length of 20 inches for a more balanced usage.
The bars on this chainsaw can handle lengths from 16 to 25 inches. But I’d caution against automatically opting for the largest size; it might be too long, pricier, and heavier than what’s needed for typical storm cleanups and yard tasks.
True to its weight, this chainsaw packs decent durability. Some complaints are specifically about its heaviness, but this feature helps the tool withstand thicker and tougher wood materials.
When you outfit this chainsaw with keen blades and the right accessories, its design really shines, making tasks like pruning, limbing, and trimming a breeze.
Stihl MS 391 Features
Overview of Specs
- Power source: Gasoline
- Engine power: 4.4 bhp
- Engine displacement: 64.1 cc
- Powerhead weight: 13.67 pounds
- Bar length: 16 to 25 inches (Recommended: 20 inches)
- Chain size: 3/8" RS3
- Chain oil capacity: 11.8 oz
- Fuel capacity: 20.3 oz
- Warranty period: One year (Personal) & three months (Commercial/Professional)
Engine Power
For a handheld tool rated for residential use, Stihl MS 391’s 4.4 bhp motor engine can handle regular yard tasks and garden maintenance. It’s especially suitable for cutting rigid wood types like oak and beech.
From my time working with wood, I’ve noticed most homeowner chainsaws usually sit between 32 cc to 45 cc. But this particular model, with its 64.1 cubic centimeters engine, definitely offers a noticeable uptick in efficiency and power.
However, it’s not the chainsaw I would recommend for demanding cutting tasks like wood milling. For such activities, you’re better off with a more powerful tool with at least 70cc motor displacement.
Bar and Chain
This Stihl chainsaw runs with RAPID™ Super 3 (RS3) full-chisel chain. Besides improving cutting speed and strength, this component includes a single-drive link that minimizes kickback and motor vibrations.
Its chain cutter features square-shaped corners and razor-liked edges. These attributes helped the chain operate smoothly with minimal friction [1].
If you maintain a sharp cutter and keep the bar lubricated regularly, you will avoid problematic resistance that may affect cutting results.
Maximum Bar Length
Although you can choose between 16 to 25 inches bar options for this gas chainsaw, I don’t recommend selecting the longest. Ultimately, your desired bar length should depend on the cutting requirements and conditions.
One of the reasons why going for the maximum length isn’t ideal is the additional weight it contributes to the powerhead. So unless you’re cleaning up thicker-than-usual wood pieces, attaching a full-on 25-inch chainsaw bar won’t be as productive as you think.
With the power and displacement MS 391 has, using a 20-inch chainsaw bar should be enough to tackle small-scale to mid-scale cutting tasks.
Besides that, going for a shorter selection also means saving more money, as the 20-inch chain is cheaper than the 25-inch options.
Chain Tensioner
Unlike typical chainsaw models, this tool has its chain tensioner strategically located at the side. Thanks to this design, operators gain more access to the adjustment screw. They’ll also have less difficulty wielding the wrench over it.
Air Filtration System
The efficiency Stihl MS 391 exhibits mainly stem from its integrated air filtration system. This pre-separation technology draws airflow within the engine through centrifugal force.
It separates the heavier and more massive dirt and dust particles before reaching the chainsaw’s air filters. This re-routing system produces less dust, leading to fewer cleaning and maintenance procedures in the long run.
Anti-Vibration System
In my experience, tools with hefty motors tend to vibrate quite a bit in use. But what’s impressive about the Stihl MS 391 is its advanced anti-vibration system, which not only spares the operator from the jitters but also protects the chainsaw’s essential parts.
Many chainsaw users also prefer models with an anti-vibration feature because it prevents inaccurate cutting results. On top of that, it also prevents user fatigue during extensive operations.
Cutting Performance
Having worked with various models from the brand, I can confidently say the MS 391 outperforms its predecessors, especially when compared to the MS 291.
This advantage comes from the unit’s higher power range and motor displacement, making it suitable for more complex tasks like felling small trees and cutting firewood pieces.
But, as I mentioned earlier, this tool belongs to the heavy-weight category. So, it can affect its cutting performance. You can minimize this drawback by selecting a smaller guide bar, but it depends on your task requirements.
On the bright side, this model includes an efficient master control lever. With the choke, throttle lock, and power switch in one location, newbie users can use this chainsaw easily.
Fuel Efficiency
If you ask me, the most impressive function of MS 391 is its IntelliCarb™ Compensating Carburetor. This advanced technology automatically adjusts the airflow and fuel ratio when the filters get clogged.
The IntelliCarb system also ensures that the chainsaw remains at its correct speed (RPM) and controls the fuel flow throughout the tool’s usage.
And since it only allows the machine to use the cleaner side of the air filters, it provides better ventilation for the carburetor. As the airflow decreases, fuel production compensates with efficiency and consistency.
Safety Features
The anti-vibration system really steps up the unit’s cutting game, reducing potential errors and slip-ups. When you’re more at ease with a tool in hand, the likelihood of unexpected mishaps naturally decreases.
It’s also safer for a chainsaw to have a lubrication system. Why? Because it keeps the chain oiled regularly, preventing the tool from turning dull and encountering mishaps throughout its usage.
The manufacturers also foresaw that kickback was inevitable for this type of tool. To prevent unwanted effects, you can activate the Stihl Quickstop feature. It’s a chain brake that automatically halts the operation when the chain and bar jammed into a material.
You’ll also find its ElastoStart function reassuring, as it won’t frustrate you with multiple tries to get the engine going. As you know, it’s a common root of accidental startups and mishaps.
Emissions
Stihl is a manufacturer with a certified “Caring for Nature” seal in every product line they launched. It’s a campaign that promises eco-friendly technologies with reduced emissions. And, of course, it includes MS 391 and other chainsaws under the brand.
The low exhaust emissions in this tool imply that it aligns with the U.S. Environmental Protection Agency and The California Air Resources Board standards.
Price and Warranty
Gas chainsaws like the Stihl MS 391 typically come with a heftier price tag compared to other standard options out there. But given its robust build and impressive capabilities, I genuinely believe it’s worth every penny.
The cost can also accumulate higher, especially if you choose a more extended chainsaw bar for your unit. Other accessories and fuel are additional expenses you should consider when using the model.
On top of the chainsaw’s perks, you can also benefit from its limited warranty policy. For units used in residential settings, the warranty covers up to one year. However, commercial warranty only ranges up to 3 months.
It’s best to stick to the official store or authorized sellers when buying this tool. Doing so ensures a smoother process if you ever need to claim the warranty.
Common Issues With Stihl MS 391
Some issue users reported about Stihl MS 391 is its heavy construction. While it’s typical for premium gas chainsaws, it’s a tricky feature for newbies, especially if you’re not strong enough or handling extended cutting operations.
If you inspect the tool closer, it’s hard to ignore its poor-quality port covers and transfer cups. These components are crucial, especially for preventing air leaks within the chainsaw.
And considering how much it weighs, pairing it with the longest guide bar available for the model isn’t recommended. It’ll only make the unit’s power-to-weight ratio suffer even further.
FAQ
Can you put a 25-inch bar on an MS391?
Yes, you can put a 25-inch bar on an MS391. However, there are better bar lengths for efficient cutting operations. Choosing a more extended bar will make the tool heavier and affect its power-to-weight ratio. It’s also more expensive than shorter ones.
What is the gas mixture for a Stihl MS 391?
The gas mixture for a Stihl MS 391 is 50:1, with the latter for oil. All gas-powered equipment under the brand comes with this requirement.
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Review Conclusion: Stihl MS 391
Similar to what Stihl MS 391 reviews say, it’s evident that this chainsaw will work more effectively in a non-regular and less demanding environment.
The tool may be powerful enough, but it won’t deliver excellent cutting results if you use it daily. Nevertheless, I can attest that the MS 391 is a reliable gasoline-powered chainsaw that’s a great option for different wood-cutting applications.
You've probably seen his down-to-earth wisdom in USA Today, Bobvila, Family Handyman, and The Spruce, where he has shared commentary and guidance on various woodworking topics.
Robert is the brain behind Sawinery, where he aims to share tips, tricks, and a passion for all things carpentry.
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