Stihl Chainsaw Bars 25 Inch: MS391 Upgrade Review (Pro Tips)

Let’s talk about chainsaws, specifically upgrading your Stihl MS391 with a 25-inch bar. The user intent behind “Stihl Chainsaw Bars 25 Inch: MS391 Upgrade Review (Pro Tips)” is clear: someone wants to know if a 25-inch bar is a good fit for their MS391, and if so, how to make the most of it. They’re likely looking for performance reviews, upgrade tips, and maybe even some troubleshooting advice.

I’ve spent years felling trees, processing timber, and preparing firewood. I’ve used everything from small limbing saws to massive milling setups. I’ve learned a lot about what works, what doesn’t, and how to get the most out of your equipment. So, let’s dive into the world of the Stihl MS391 and the benefits (and potential drawbacks) of pairing it with a longer 25-inch bar.

Upgrading Your Stihl MS391 with a 25-Inch Bar: A Pro’s Guide

The Stihl MS391 is a solid, dependable workhorse. It’s a popular choice for landowners, farmers, and even smaller logging operations. It offers a good balance of power and weight, making it versatile for a range of tasks. However, the stock bar length (usually around 18-20 inches) can sometimes feel limiting, especially when dealing with larger trees. That’s where the 25-inch bar comes in.

Is a 25-Inch Bar Right for Your MS391?

Before you rush out and buy a new bar, it’s crucial to consider whether it’s the right choice for your MS391 and the type of work you do. A longer bar increases your reach and allows you to fell larger trees in a single pass. However, it also puts more strain on the saw’s engine and requires more skill to operate safely and effectively.

Key Considerations:

• Tree Size: What’s the typical diameter of the trees you’ll be cutting? If you’re consistently felling trees with a diameter close to or exceeding the length of your current bar, a 25-inch bar will significantly improve your efficiency.
• Wood Type: Hardwoods like oak and maple require more power than softwoods like pine and fir. If you primarily cut hardwoods, you might find the MS391 struggles a bit with a 25-inch bar.
• Your Experience: Operating a chainsaw with a longer bar requires more control and experience. If you’re a beginner, I recommend gaining more experience with a shorter bar before making the jump.
• Saw Condition: Is your MS391 in good working order? A worn engine or dull chain will only exacerbate the challenges of using a longer bar.
• Bar and Chain Quality: Don’t cheap out on the bar and chain. A high-quality bar will be more durable and provide better chain support, leading to smoother cuts and less wear on your saw. A good chain will stay sharp longer and cut more efficiently.

My Experience:

I remember years ago, I was working on a property clearing some overgrown oak trees. My trusty MS290 (a very similar saw to the MS391) with an 18-inch bar was struggling to get through some of the larger trunks. I finally decided to try a 20-inch bar, and it made a world of difference. The increased reach allowed me to fell the trees more safely and efficiently. However, I also noticed the saw was working harder, and I had to be extra careful to maintain a sharp chain and proper cutting technique. I later upgraded to a MS362 with a 25-inch bar for larger jobs.

Benefits of a 25-Inch Bar on the MS391

• Increased Felling Capacity: The most obvious benefit is the ability to fell larger trees. This reduces the need for multiple cuts and saves time and effort.
• Improved Reach: A longer bar allows you to reach branches and limbs that would otherwise be inaccessible. This is particularly useful for pruning and limbing.
• Enhanced Leverage: The added length provides more leverage, making it easier to control the saw and maintain a straight cut.
• Reduced Kickback Risk (Potentially): While counterintuitive, in some situations, a longer bar can reduce kickback risk. This is because the longer bar allows you to keep the nose of the bar further away from obstructions. However, this is highly dependent on proper technique and experience. Always be aware of the kickback zone.

Potential Drawbacks of a 25-Inch Bar on the MS391

• Increased Strain on the Engine: A longer bar requires more power to drive the chain. This can put extra stress on the engine and potentially shorten its lifespan.
• Reduced Cutting Speed: The MS391 might feel a bit sluggish with a 25-inch bar, especially when cutting hardwoods. You might need to reduce your cutting pressure and allow the saw to do the work.
• Increased Weight and Fatigue: The added length and weight of the bar can make the saw more tiring to use, especially for extended periods.
• Increased Kickback Risk (Potentially): As mentioned earlier, a longer bar can increase kickback risk if not used properly. The larger surface area of the bar nose makes it more susceptible to catching on obstructions.
• Reduced Maneuverability: A longer bar makes the saw less maneuverable, especially in tight spaces.

Selecting the Right 25-Inch Bar and Chain

Choosing the right bar and chain is crucial for maximizing performance and safety.

Bar Selection:

• Brand: Stihl bars are generally excellent, but there are other reputable brands like Oregon and Tsumura that offer high-quality options.
• Type: Look for a laminated bar with a replaceable sprocket nose. This type of bar is durable and easy to maintain. Solid bars are also an option, but they are generally heavier and more expensive.
• Gauge and Drive Link Count: Make sure the bar’s gauge and drive link count match your chainsaw’s specifications. The MS391 typically uses a .063″ gauge chain with a 3/8″ pitch. The drive link count for a 25-inch bar will vary depending on the specific bar model, but it’s usually around 84. Always double-check the manufacturer’s recommendations.
• Hardness: Look for a bar made with hardened steel for increased durability.

Chain Selection:

• Type: There are several types of chainsaw chains available, each with its own advantages and disadvantages.
  • Full Chisel: These chains have aggressive cutting teeth and are ideal for clean wood. They cut quickly but dull easily.
  • Semi-Chisel: These chains are more forgiving than full chisel chains and are better suited for dirty or knotty wood. They’re a good all-around choice.
  • Low-Profile: These chains have rounded cutting teeth and are designed for safety. They’re a good choice for beginners.
• Pitch and Gauge: As with the bar, make sure the chain’s pitch and gauge match your chainsaw’s specifications.
• Brand: Stihl, Oregon, and Carlton are all reputable chain brands.
• Consider a Ripping Chain: If you plan on using the 25-inch bar for milling, consider a ripping chain. Ripping chains are designed to cut along the grain of the wood, making them more efficient for milling.

Example:

For my MS391 upgrade, I’d likely choose an Oregon 25-inch Power Match bar (.063″ gauge, 3/8″ pitch, 84 drive links) paired with an Oregon 72LPX chain (semi-chisel, .063″ gauge, 3/8″ pitch). This combination offers a good balance of performance, durability, and affordability.

Installing the 25-Inch Bar and Chain

Installing the new bar and chain is a straightforward process.

Step-by-Step Guide:

1. Safety First: Always wear gloves and safety glasses when working with chainsaws. Disconnect the spark plug wire to prevent accidental starting.
2. Remove the Old Bar and Chain: Loosen the bar nuts and remove the side cover. Carefully remove the old bar and chain.
3. Inspect the Sprocket: Check the sprocket for wear and tear. If it’s worn, replace it. A worn sprocket can damage the chain and reduce cutting performance.
4. Install the New Bar: Place the new bar onto the mounting studs, ensuring the chain tensioner pin is properly aligned.
5. Install the New Chain: Drape the chain around the bar, ensuring the cutting teeth are facing in the correct direction (they should point towards the nose of the bar on the top).
6. Align the Chain with the Sprocket: Make sure the chain drive links are properly seated in the sprocket.
7. Reinstall the Side Cover: Place the side cover back onto the chainsaw and tighten the bar nuts finger-tight.
8. Adjust the Chain Tension: Use the chain tensioner to adjust the chain tension. The chain should be snug against the bar but still able to be pulled around by hand. A properly tensioned chain will have approximately 1/8″ to 1/4″ of sag on the bottom of the bar.
9. Tighten the Bar Nuts: Once the chain tension is properly adjusted, tighten the bar nuts securely.
10. Check the Chain Tension Again: After tightening the bar nuts, recheck the chain tension and make any necessary adjustments.
11. Lubricate the Chain: Fill the chain oil reservoir with high-quality bar and chain oil.

Pro Tip:

When installing a new chain, I like to soak it in bar and chain oil overnight. This helps to lubricate the chain and prevent it from stretching prematurely.

Using the 25-Inch Bar Safely and Effectively

Operating a chainsaw with a longer bar requires extra caution and skill.

Safety Precautions:

• Wear Proper Safety Gear: Always wear a helmet with a face shield, hearing protection, gloves, chaps, and sturdy boots.
• Maintain a Firm Grip: Keep both hands firmly on the chainsaw at all times.
• Maintain Proper Stance: Stand with your feet shoulder-width apart and your weight evenly distributed.
• Be Aware of Your Surroundings: Check for obstacles such as branches, rocks, and power lines.
• Avoid Cutting Above Shoulder Height: Cutting above shoulder height is dangerous and can lead to loss of control.
• Never Cut with the Tip of the Bar: The tip of the bar is the kickback zone. Avoid cutting with the tip of the bar at all costs.
• Use Proper Felling Techniques: If you’re felling trees, use proper felling techniques to ensure the tree falls in the desired direction.
• Keep the Chain Sharp: A dull chain is dangerous and inefficient. Sharpen the chain regularly.
• Inspect the Chainsaw Regularly: Check the chainsaw for any signs of damage or wear and tear.
• Take Breaks: Chainsaw operation can be physically demanding. Take frequent breaks to avoid fatigue.
• Never Operate a Chainsaw Under the Influence: This should be obvious, but it’s worth repeating. Never operate a chainsaw under the influence of alcohol or drugs.

Cutting Techniques:

• Let the Saw Do the Work: Don’t force the saw through the wood. Let the weight of the saw and the sharpness of the chain do the work.
• Maintain a Consistent Cutting Speed: Avoid jerky or erratic movements.
• Use a Guide: When cutting long, straight cuts, use a guide to ensure a straight line.
• Avoid Pinching: Pinching occurs when the bar gets stuck in the cut. To avoid pinching, use wedges or limbing cuts to relieve pressure on the bar.
• Be Aware of Wood Tension: Wood under tension can snap back and cause injury. Be careful when cutting wood that is under tension.

Pro Tip:

When felling trees, I always use a felling wedge to help direct the fall of the tree. This prevents the tree from falling in an unexpected direction and potentially causing damage or injury. I prefer plastic wedges, as metal wedges can damage the chain if you accidentally hit them.

Maintaining Your MS391 with a 25-Inch Bar

Proper maintenance is essential for keeping your MS391 running smoothly and reliably, especially when using a longer bar.

Maintenance Schedule:

• Daily:
  • Check the chain tension and adjust as needed.
  • Sharpen the chain.
  • Clean the air filter.
  • Check the fuel and oil levels.
  • Inspect the chainsaw for any signs of damage or wear and tear.
• Weekly:
  • Clean the spark plug.
  • Clean the cooling fins.
  • Grease the bar tip sprocket.
  • Inspect the bar for wear and tear.
• Monthly:
  • Replace the air filter.
  • Inspect the fuel filter.
  • Inspect the chain oil filter.
  • Check the anti-vibration mounts.
• Annually:
  • Have the chainsaw professionally serviced.

Specific Maintenance Tips for a 25-Inch Bar:

• Pay Close Attention to Chain Tension: A longer bar is more susceptible to chain stretch. Check the chain tension frequently and adjust as needed.
• Lubricate the Bar Tip Sprocket Regularly: The bar tip sprocket is critical for smooth chain operation. Grease it regularly to prevent wear and tear.
• Inspect the Bar for Wear and Tear: Check the bar rails for wear and tear. If the rails are worn, the chain will not run smoothly.
• Consider a Bar Rail Dresser: A bar rail dresser can be used to restore worn bar rails.

Pro Tip:

I always use a high-quality bar and chain oil. Cheap oil can damage the chain and bar and reduce cutting performance. Stihl and Oregon both make excellent bar and chain oils. I also prefer using a fuel stabilizer in my gasoline to prevent the fuel from going stale, especially if the saw will be sitting for an extended period.

Case Study: Felling a Large Oak with an MS391 and 25-Inch Bar

Let’s walk through a real-world scenario: felling a large oak tree with the MS391 and a 25-inch bar.

The Situation:

I needed to remove a large oak tree that was leaning precariously close to a barn. The tree was approximately 30 inches in diameter at the base. The MS391 was equipped with a new Oregon 25-inch Power Match bar and a sharp Oregon 72LPX chain.

The Process:

1. Planning: I carefully assessed the tree and its surroundings. I identified the lean of the tree and determined the safest direction for it to fall. I also cleared any obstacles from the felling zone.
2. Safety Precautions: I put on my safety gear: helmet with face shield, hearing protection, gloves, chaps, and sturdy boots.
3. Notch Cut: I made a precise notch cut on the side of the tree facing the direction I wanted it to fall. The notch cut was approximately one-third of the tree’s diameter.
4. Back Cut: I made a back cut on the opposite side of the tree, slightly above the notch cut. I left a hinge of approximately 2 inches to control the fall of the tree.
5. Felling Wedge: As I approached the hinge with the back cut, I inserted a felling wedge into the cut. This helped to prevent the tree from pinching the bar and also helped to direct the fall of the tree.
6. Final Cut: Once the wedge was firmly in place, I made the final cut through the hinge.
7. The Fall: The tree fell in the desired direction, landing safely away from the barn.
8. Limbing and Bucking: After the tree was on the ground, I limbed it using the MS391. I then bucked the trunk into manageable sections for firewood.

Lessons Learned:

• The 25-inch bar was essential for felling this large tree in a single pass.
• A sharp chain and proper cutting technique were critical for maximizing the saw’s performance.
• The felling wedge was essential for controlling the fall of the tree.
• The MS391 performed well, but it was working hard. I wouldn’t recommend using it for consistently felling trees of this size. For larger trees, a more powerful saw is recommended.

Strategic Advantages of Using a 25-Inch Bar for Firewood Prep

Beyond felling, a 25-inch bar can be advantageous for firewood preparation itself.

• Bucking Large Rounds: When dealing with large-diameter logs, a longer bar allows you to buck them into firewood-sized rounds without having to roll them over repeatedly. This saves time and effort and reduces the risk of injury.
• Splitting Assistance (Indirectly): While you don’t split with a chainsaw, accurately bucking consistent round sizes makes the splitting process itself more efficient, especially when using a log splitter. Consistent round sizes feed better into the splitter.
• Processing Crooked or Unwieldy Logs: Sometimes you encounter logs that are crooked or have unusual shapes. A longer bar can help you navigate these challenges and buck them into usable pieces.

Understanding Wood Moisture Content for Firewood

A crucial aspect of firewood preparation is understanding wood moisture content.

• Green Wood: Freshly cut wood is considered “green.” It has a high moisture content (often over 50%) and is difficult to burn efficiently. It produces a lot of smoke and creosote, which can be dangerous.
• Seasoned Wood: Seasoned wood has been allowed to dry for a period of time. The moisture content is typically below 20%. Seasoned wood burns hotter, cleaner, and more efficiently.

Drying Methods:

• Air Drying: The most common method is to stack the wood in a single row, off the ground, in a sunny and windy location. This allows air to circulate around the wood and dry it out. The drying time depends on the wood type, climate, and stacking method, but it typically takes 6-12 months.
• Kiln Drying: Kiln drying is a faster method of drying wood. The wood is placed in a kiln and heated to a high temperature. This dries the wood in a matter of days or weeks. Kiln-dried wood is typically more expensive than air-dried wood.

Moisture Meters:

A moisture meter is a valuable tool for determining the moisture content of wood. There are two main types of moisture meters: pin meters and pinless meters. Pin meters measure the moisture content by inserting two pins into the wood. Pinless meters measure the moisture content using radio frequency waves.

Target Moisture Content:

The ideal moisture content for firewood is below 20%. At this moisture content, the wood will burn hot and clean.

My Drying Setup:

I stack my firewood on pallets to keep it off the ground. I also cover the top of the stack with a tarp to protect it from rain and snow, but I leave the sides open to allow air to circulate. I use a moisture meter to check the moisture content of the wood before burning it. My target moisture content is 15-20%.

Log Splitting Techniques

Once you’ve bucked your logs into firewood rounds, the next step is splitting them.

• Manual Splitting: This involves using an axe or maul to split the wood by hand. It’s a great workout, but it can be physically demanding, especially when dealing with large or knotty logs.
• Hydraulic Log Splitters: These machines use hydraulic power to split the wood. They’re much faster and easier to use than manual splitting, especially for large volumes of wood.

Types of Hydraulic Log Splitters:

• Horizontal Log Splitters: The most common type of log splitter. The log is placed horizontally on the splitter, and the ram pushes it against a wedge.
• Vertical Log Splitters: The log is placed vertically on the splitter, and the ram pushes the wedge down onto the log. Vertical log splitters are easier to use for large logs, as you don’t have to lift them as high.

Tonnage:

Log splitters are rated by tonnage, which is the amount of force they can exert. A 20-ton log splitter is sufficient for most firewood splitting needs. However, if you regularly split large or knotty logs, you might want to consider a 25-ton or even a 30-ton log splitter.

Safety Precautions:

• Wear Safety Glasses: Always wear safety glasses when splitting wood, whether manually or with a log splitter.
• Wear Gloves: Wear gloves to protect your hands.
• Use Proper Technique: Use proper technique to avoid injury.
• Keep a Safe Distance: Keep a safe distance from the log splitter while it’s in operation.
• Never Place Your Hands in the Splitting Zone: This is extremely dangerous and can result in serious injury.

My Log Splitting Setup:

I use a 27-ton horizontal/vertical log splitter. It’s powerful enough to split even the toughest logs. I always wear safety glasses and gloves when splitting wood. I also make sure to keep a safe distance from the splitter while it’s in operation.

Stacking Firewood for Optimal Drying

Proper firewood stacking is crucial for efficient drying.

• Elevate the Wood: Stack the wood on pallets or other materials to keep it off the ground. This allows air to circulate underneath the wood and prevents it from absorbing moisture from the ground.
• Single Row Stacking: Stack the wood in single rows, with the rows running in the direction of the prevailing wind. This allows air to circulate around the wood and dry it out.
• Leave Space Between Rows: Leave space between the rows to allow for air circulation.
• Cover the Top of the Stack: Cover the top of the stack with a tarp to protect it from rain and snow. However, leave the sides open to allow air to circulate.
• Consider a Holzhaufen: A Holzhaufen is a circular stack of firewood that is self-supporting. It’s an efficient way to stack firewood, but it requires some skill to build properly.

My Stacking Method:

I stack my firewood on pallets in single rows, with the rows running in the direction of the prevailing wind. I leave about 6 inches of space between the rows. I cover the top of the stack with a tarp, but I leave the sides open. This method has proven to be very effective for drying firewood in my climate.

Cost Considerations for Upgrading to a 25-Inch Bar

Let’s factor in the cost of this upgrade.

• Bar Cost: A quality 25-inch bar can range from $75 to $150, depending on the brand and features.
• Chain Cost: A good quality chain for a 25-inch bar typically costs between $30 and $60.
• Maintenance Costs: Expect slightly higher maintenance costs due to increased chain wear and potential engine strain. This might include more frequent chain sharpening, bar lubrication, and potential engine repairs in the long run.
• Fuel Consumption: The MS391 will likely consume slightly more fuel with a longer bar, especially when cutting hardwoods.

Return on Investment (ROI):

The ROI of upgrading to a 25-inch bar depends on your specific needs and usage patterns. If you frequently fell larger trees or process large volumes of firewood, the increased efficiency and capacity can quickly offset the initial cost. However, if you only occasionally need the extra reach, the upgrade might not be worth the investment.

Final Thoughts and Recommendations

Upgrading your Stihl MS391 with a 25-inch bar can be a worthwhile investment if you frequently deal with larger trees or need the added reach for pruning and limbing. However, it’s essential to consider the potential drawbacks, such as increased strain on the engine and reduced cutting speed.

My Recommendations:

• Assess Your Needs: Carefully consider the type of work you do and the size of the trees you’ll be cutting.
• Choose Quality Components: Invest in a high-quality bar and chain.
• Practice Proper Technique: Learn and practice proper chainsaw operating techniques.
• Maintain Your Saw: Keep your chainsaw properly maintained.
• Prioritize Safety: Always prioritize safety when operating a chainsaw.

Next Steps:

1. Research: Research different 25-inch bars and chains that are compatible with your MS391.
2. Read Reviews: Read online reviews from other users to get their feedback on different products.
3. Consult with a Professional: Talk to a chainsaw professional at your local hardware store or outdoor power equipment dealer.
4. Make Your Purchase: Purchase the bar and chain that best suits your needs and budget.
5. Install and Test: Install the new bar and chain and test it out in a safe and controlled environment.

By following these steps, you can make an informed decision about whether or not to upgrade your Stihl MS391 with a 25-inch bar and enjoy the benefits of increased cutting capacity and reach. Remember, safety is paramount. Always wear proper safety gear and practice safe operating techniques. Happy cutting!

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