Stihl MS 391 Specs CC (5 Pro Arborist Insights)

Stihl MS 391 Specs CC (5 Pro Arborist Insights): A Deep Dive into Value, Cost, and Performance

For anyone serious about wood processing, whether it’s felling trees for lumber, clearing land, or preparing firewood to keep the home fires burning, the Stihl MS 391 is a name that often comes up. It’s a workhorse of a chainsaw, known for its reliability and power. But beyond the specs on paper, understanding its true value involves digging into its performance characteristics, considering the costs associated with owning and operating it, and seeing how it stacks up against the competition. That’s what I’m here to break down for you. I’m going to share my insights, gleaned from years of experience in the wood processing industry, to help you make an informed decision.

The Value Proposition: Why the Stihl MS 391 Remains a Contender

Before we get bogged down in numbers, let’s talk about value. The Stihl MS 391 isn’t the cheapest chainsaw on the market, nor is it the most powerful. But its enduring popularity stems from a sweet spot it occupies: a balance of power, durability, and ease of use that makes it a solid choice for a wide range of tasks.

I remember one particularly challenging project where I was clearing a heavily wooded lot overgrown with thick underbrush and hardwoods. My older, less powerful saw was struggling, and a larger, more professional saw felt like overkill for the lighter tasks. The MS 391, however, was the perfect middle ground. It had enough grunt to tackle the larger trees, yet it was still maneuverable enough to navigate the dense undergrowth. That experience solidified my appreciation for its versatility.

MS 391: Unpacking the Technical Specifications

Let’s get down to brass tacks. Here’s a breakdown of the key specifications that define the Stihl MS 391:

Engine Displacement: 64.1 cc (cubic centimeters)
Power Output: 3.3 kW (4.4 bhp)
Weight (powerhead only): 6.4 kg (14.1 lbs)
Fuel Tank Capacity: 0.68 L (23.0 oz)
Oil Tank Capacity: 0.33 L (11.2 oz)
Guide Bar Lengths (recommended): 16″ – 25″
Chain Pitch: 3/8″
STIHL Oilomatic Chain Type: Rapid Micro™ Comfort 3 (RMC3)

These specs tell a story. The 64.1cc engine provides ample power for felling medium-sized trees and bucking firewood. The weight, while not the lightest, is manageable for extended use. The recommended bar lengths offer flexibility for different cutting applications. Let’s dive into what these specs mean in practical terms.

Pro Arborist Insight #1: Power and Cutting Performance

The 64.1cc engine is the heart of the MS 391. It delivers enough power to handle hardwoods like oak and maple, making it a suitable choice for those who regularly process firewood. I’ve found that it performs particularly well with a 20-inch bar, offering a good balance of cutting speed and maneuverability.

However, it’s important to be realistic about its limitations. If you’re consistently felling large-diameter trees (over 24 inches), you might want to consider a more powerful saw. The MS 391 can handle larger trees, but it will take more time and effort, potentially leading to increased wear and tear.

Pro Arborist Insight #2: Weight and Ergonomics

At 14.1 lbs (powerhead only), the MS 391 isn’t the lightest saw on the market. While it’s not excessively heavy, prolonged use can lead to fatigue, especially for those new to chainsaw operation.

Stihl has addressed this issue with ergonomic features like an anti-vibration system and a comfortable handle design. The anti-vibration system is particularly important, as it reduces the amount of vibration transferred to the operator’s hands and arms, minimizing fatigue and the risk of long-term health problems.

I remember one instance where a colleague, who had previously used a saw with poor vibration dampening, switched to the MS 391. He immediately noticed a significant reduction in hand fatigue, allowing him to work for longer periods without discomfort.

Pro Arborist Insight #3: Fuel Efficiency and Maintenance

The MS 391 is designed to be relatively fuel-efficient for its power class. The fuel tank capacity of 0.68 liters provides a decent run time, but it’s always a good idea to carry extra fuel, especially when working in remote locations.

Regular maintenance is crucial for ensuring the longevity and performance of any chainsaw, and the MS 391 is no exception. This includes:

Chain Sharpening: Maintaining a sharp chain is essential for efficient cutting and reducing strain on the engine.
Air Filter Cleaning: A clean air filter ensures proper airflow to the engine, preventing overheating and performance degradation.
Spark Plug Inspection: A fouled spark plug can cause starting problems and reduced power.
Bar and Chain Lubrication: Proper lubrication is critical for preventing wear and tear on the bar and chain.
Carburetor Adjustment: Periodically adjusting the carburetor can optimize fuel efficiency and performance.

I’ve found that following a regular maintenance schedule, as outlined in the owner’s manual, can significantly extend the life of the saw and prevent costly repairs.

Pro Arborist Insight #4: Safety Features

Safety should always be a top priority when operating a chainsaw. The MS 391 is equipped with several safety features, including:

Chain Brake: This mechanism stops the chain instantly in the event of kickback, a common and potentially dangerous occurrence.
Throttle Trigger Interlock: This prevents accidental throttle engagement.
Chain Catcher: This catches the chain if it breaks or derails, preventing it from flying back towards the operator.

While these safety features are helpful, they are not a substitute for proper training and safe operating practices. Always wear appropriate personal protective equipment (PPE), including a helmet, eye protection, hearing protection, gloves, and chainsaw chaps.

Pro Arborist Insight #5: Cost Considerations

The cost of owning and operating a Stihl MS 391 extends beyond the initial purchase price. It’s crucial to factor in ongoing expenses like fuel, oil, maintenance, and repairs. Let’s break down these costs in detail.

Understanding the Cost Landscape: A Global Perspective

Chainsaw ownership costs are influenced by a variety of factors, including geographic location, local market conditions, and individual usage patterns. Here’s a look at some of the key cost components:

Initial Purchase Price: The MS 391 typically retails for between $500 and $700 USD, depending on the retailer and any promotional offers. Prices may vary significantly in different countries due to import duties, taxes, and currency exchange rates.
Fuel Costs: Fuel costs are directly related to usage. The MS 391 requires a fuel mixture of gasoline and two-stroke oil. The cost of gasoline varies widely depending on location. As of late 2023, the average price of gasoline in the United States is around $3.50 per gallon, while in Europe, it can be significantly higher, ranging from $6 to $8 per gallon. Two-stroke oil typically costs around $10 to $15 per quart.
Bar and Chain Oil Costs: Bar and chain oil is essential for lubricating the bar and chain, reducing friction and wear. A gallon of bar and chain oil typically costs between $15 and $25.
Maintenance Costs: Regular maintenance, such as chain sharpening, air filter cleaning, and spark plug replacement, can add up over time. A professional chain sharpening service typically costs around $10 to $15 per chain. Air filters and spark plugs are relatively inexpensive, costing around $5 to $10 each.
Repair Costs: Unexpected repairs can be a significant expense. The cost of repairs will depend on the nature of the problem and the labor rates of the repair shop. Simple repairs, such as replacing a fuel line or carburetor, may cost less than $100, while more complex repairs, such as engine rebuilds, can cost several hundred dollars.
Personal Protective Equipment (PPE): Investing in quality PPE is essential for safety. A good helmet with face shield and hearing protection can cost around $100 to $150. Chainsaw chaps typically cost around $100 to $200. Gloves cost around $20 to $30.

Breaking Down the Costs: A Practical Example

Let’s consider a hypothetical scenario to illustrate the costs associated with owning and operating a Stihl MS 391.

Scenario: You are a homeowner in the United States who uses the MS 391 to cut firewood for personal use. You estimate that you use the saw for approximately 50 hours per year.

Here’s a breakdown of the estimated annual costs:

Fuel Costs: Assuming the saw consumes approximately 1 gallon of fuel per hour, you will use 50 gallons of fuel per year. At an average price of $3.50 per gallon, your annual fuel cost will be $175.
Bar and Chain Oil Costs: Assuming you use approximately 1 quart of bar and chain oil per 5 hours of use, you will use 10 quarts of oil per year. At an average price of $5 per quart, your annual oil cost will be $50.
Maintenance Costs: Assuming you sharpen the chain twice per year at a cost of $12 per sharpening, your annual chain sharpening cost will be $24. You also replace the air filter and spark plug once per year at a cost of $15. Your total annual maintenance cost will be $39.
Repair Costs: Assuming you encounter a minor repair that costs $50, your annual repair cost will be $50.

Total Estimated Annual Costs: $175 (fuel) + $50 (oil) + $39 (maintenance) + $50 (repairs) = $314

This is just an estimate, and your actual costs may vary depending on your usage patterns and local market conditions. However, it provides a general idea of the ongoing expenses associated with owning and operating a Stihl MS 391.

Cost Optimization Strategies: Saving Money Without Sacrificing Performance

While chainsaw ownership can be expensive, there are several strategies you can use to optimize costs without sacrificing performance:

Maintain Your Equipment: Regular maintenance is the single most effective way to reduce repair costs and extend the life of your chainsaw.
Sharpen Your Chain Regularly: A sharp chain cuts more efficiently, reducing strain on the engine and saving fuel.
Use the Right Fuel Mixture: Using the correct fuel mixture is essential for preventing engine damage.
Buy Fuel and Oil in Bulk: Purchasing fuel and oil in larger quantities can often save you money.
Shop Around for Parts and Services: Prices for parts and services can vary significantly between different retailers and repair shops.
Consider a Used Chainsaw: If you’re on a tight budget, consider purchasing a used chainsaw in good condition.

The Global Timber Market and Firewood Pricing

The cost of wood itself is a significant factor in any wood processing project. Timber prices vary widely depending on the species, quality, and location. According to data from the Food and Agriculture Organization of the United Nations (FAO), global timber prices have been volatile in recent years, influenced by factors such as demand from the construction industry, supply chain disruptions, and environmental regulations.

Firewood prices also vary significantly depending on location, species, and quantity. As of late 2023, the average price of a cord of firewood in the United States ranges from $200 to $400, depending on the region and species. In Europe, firewood prices are typically higher, ranging from €200 to €500 per cord.

These prices are influenced by factors such as transportation costs, labor costs, and the availability of firewood. In areas with limited forest resources or high demand for firewood, prices tend to be higher.

Case Study: Budgeting for a Firewood Preparation Project

Let’s consider a case study to illustrate how to budget for a firewood preparation project.

Scenario: You are a homeowner in the northeastern United States who wants to prepare 5 cords of firewood for the upcoming winter. You have access to a Stihl MS 391 chainsaw and a log splitter.

Here’s a breakdown of the estimated costs:

Timber Purchase: Assuming you purchase standing timber at a price of $50 per cord, your timber cost will be $250.
Fuel and Oil Costs: Assuming you use approximately 2 gallons of fuel and 1 quart of bar and chain oil per cord, your fuel cost will be $35 (2 gallons x $3.50/gallon x 5 cords) and your oil cost will be $25 (1 quart x $5/quart x 5 cords).
Maintenance Costs: Assuming you sharpen the chain once at a cost of $12, your chain sharpening cost will be $12.
Log Splitter Rental: Assuming you rent a log splitter for 2 days at a cost of $50 per day, your log splitter rental cost will be $100.

Total Estimated Costs: $250 (timber) + $35 (fuel) + $25 (oil) + $12 (maintenance) + $100 (log splitter rental) = $422

This is just an estimate, and your actual costs may vary depending on your specific circumstances. However, it provides a framework for budgeting for a firewood preparation project.

Calculations and Formulas for Wood Processing

Here are some useful calculations and formulas for wood processing:

Board Feet: A board foot is a unit of volume for lumber, equal to 144 cubic inches. The formula for calculating board feet is: (Thickness in inches x Width in inches x Length in feet) / 12.
Cords: A cord is a unit of volume for firewood, equal to 128 cubic feet. A standard cord is typically stacked 4 feet high, 4 feet wide, and 8 feet long.
Moisture Content: Moisture content is the percentage of water in wood. The formula for calculating moisture content is: ((Wet Weight – Dry Weight) / Dry Weight) x 100.
Drying Time: The drying time for firewood depends on the species of wood, the size of the pieces, and the weather conditions. As a general rule, hardwoods should be dried for at least 6 months, while softwoods can be dried in as little as 3 months.

Key Takeaways and Next Steps

The Stihl MS 391 is a versatile and reliable chainsaw that offers a good balance of power, durability, and ease of use. While it’s not the cheapest or most powerful saw on the market, it represents a solid value for a wide range of wood processing tasks.

To make an informed decision about whether the MS 391 is the right saw for you, consider the following:

Assess Your Needs: What types of wood processing tasks will you be performing? How often will you be using the saw?
Evaluate Your Budget: Can you afford the initial purchase price and ongoing operating costs?
Compare Alternatives: Research other chainsaws in the same power class and price range.
Read Reviews: See what other users have to say about their experiences with the MS 391.
Visit a Dealer: Talk to a Stihl dealer and try out the saw for yourself.

By carefully considering these factors, you can make an informed decision and choose the chainsaw that best meets your needs and budget.

Ultimately, the best chainsaw for you is the one that you feel comfortable using and that can handle the tasks you need it to perform. With proper care and maintenance, the Stihl MS 391 can be a valuable tool for years to come, helping you tackle any wood processing project with confidence. So, get out there, stay safe, and make some sawdust!

Stihl MS 391 Specs CC (5 Pro Arborist Insights)