MS391 Specs Guide (7 Pro Tips For Optimal Wood Processing)

Did you know that improper chainsaw maintenance accounts for over 50% of chainsaw-related injuries? This shocking statistic highlights the importance of understanding your equipment and using it correctly. Today, I’m diving deep into the Stihl MS391 chainsaw, a workhorse that, when properly understood and maintained, can significantly enhance your wood processing efficiency. I’ll share my experiences, unique insights, and practical tips to help you get the most out of this powerful tool.

MS391 Specs Guide: 7 Pro Tips for Optimal Wood Processing

The Stihl MS391 is a mid-range chainsaw often favored by homeowners and professionals alike for its balance of power and weight. It’s not the lightest saw on the market, nor is it the most powerful, but it occupies a sweet spot that makes it versatile for various tasks, from felling smaller trees to bucking firewood. Over the years, I’ve used the MS391 extensively, and I’ve learned a few tricks to maximize its performance and longevity. This guide aims to share those insights with you.

Understanding the MS391 Specifications

Before we dive into the pro tips, let’s establish a solid foundation by understanding the key specifications of the MS391:

Engine Displacement: 64.1 cc (3.9 cu. in.)
Power Output: 3.3 kW (4.4 bhp)
Weight (powerhead only): 6.4 kg (14.1 lbs)
Fuel Capacity: 0.68 L (23.0 oz)
Oil Capacity: 0.35 L (11.8 oz)
Recommended Bar Length: 16-20 inches
Chain Pitch: 3/8″
Oilomatic Chain Type: Rapid Micro (RM) or Rapid Duro (RD)

These specs tell a story. The 64.1 cc engine provides ample power for most tasks, while the weight, though not featherlight, is manageable for extended use. The recommended bar length is crucial; exceeding it can strain the engine and reduce cutting efficiency.

Pro Tip 1: Mastering the Art of Chain Selection

Choosing the right chain for your MS391 is paramount. Stihl offers various chains, but the Rapid Micro (RM) and Rapid Duro (RD) are common choices.

Rapid Micro (RM): This chain offers a smooth cut and is ideal for cleaner wood. It’s easier to sharpen and generally preferred for firewood processing.
Rapid Duro (RD): This chain features carbide-tipped cutters, making it more durable and resistant to dulling, especially when cutting dirty or abrasive wood. However, it’s more challenging to sharpen.

My Experience: I once attempted to cut through a pile of reclaimed lumber riddled with hidden nails using an RM chain. The result? A quickly dulled chain and a frustrating afternoon. Switching to an RD chain saved the day and significantly increased my productivity.

Actionable Advice: Consider the type of wood you’ll be cutting most often. For clean wood, RM is excellent. For dirty or abrasive wood, invest in an RD chain. A sharp chain is a safe and efficient chain. According to a study by the US Forest Service, a dull chain can increase cutting time by up to 50% and significantly raise the risk of kickback.

Pro Tip 2: Optimizing Carburetor Tuning for Peak Performance

The carburetor is the heart of your MS391, regulating the air-fuel mixture. Proper tuning ensures optimal performance and fuel efficiency. Here’s a basic guide:

L (Low-speed): Adjusts the fuel mixture at idle and low RPMs.
H (High-speed): Adjusts the fuel mixture at high RPMs.
LA (Idle Speed): Adjusts the engine’s idle speed.

The Process:

Warm-up: Start the saw and let it warm up for a few minutes.
Idle Speed: Adjust the LA screw until the chain stops moving at idle.
Low-Speed: Slowly turn the L screw until the engine runs smoothly and accelerates cleanly without hesitation.
High-Speed: This is best left to professionals with tachometers. However, a general rule is to ensure the engine doesn’t sound “lean” (high-pitched and strained) at full throttle.

Caution: Over-leaning the mixture (too much air, not enough fuel) can damage the engine. If you’re unsure, consult a qualified technician.

Data Point: A properly tuned carburetor can improve fuel efficiency by up to 15% and reduce emissions.

Pro Tip 3: Mastering the Art of Bar and Chain Maintenance

The bar and chain are your direct interface with the wood, so their maintenance is crucial.

Chain Sharpening: Regularly sharpen your chain using a file and guide. Maintain the correct angles and depth gauge settings. A dull chain is not only inefficient but also dangerous.
Bar Maintenance: Clean the bar groove regularly to remove sawdust and debris. Check for burrs and file them down. Flip the bar periodically to ensure even wear.
Chain Tension: Ensure the chain tension is correct. It should be snug but still able to be pulled around the bar by hand.

My Story: I once neglected to clean the bar groove, leading to excessive friction and premature bar wear. The bar eventually pinched the chain, causing a dangerous kickback. This experience taught me the importance of diligent maintenance.

Actionable Advice: Invest in a good quality chain sharpening kit and learn how to use it properly. A well-maintained bar and chain will last longer, cut more efficiently, and improve safety.

Pro Tip 4: Fuel and Oil: The Lifeblood of Your MS391

Using the correct fuel and oil is essential for the longevity of your MS391.

Fuel: Use high-quality gasoline with a minimum octane rating of 89. Stihl recommends using their MotoMix pre-mixed fuel, which contains a synthetic oil and stabilizers.
Oil: Use Stihl HP Ultra two-stroke oil or a similar high-quality synthetic oil. Mix the oil with the gasoline at the recommended ratio (typically 50:1).
Chain Oil: Use a high-quality bar and chain oil to lubricate the chain and bar. Stihl BioPlus is an environmentally friendly option.

Unique Insight: Ethanol-blended gasoline can damage small engines. If you must use ethanol-blended fuel, use a fuel stabilizer to prevent corrosion and fuel degradation.

Data Point: Using the correct fuel and oil can extend the life of your engine by up to 50%.

Pro Tip 5: Safe Starting Procedures: Minimizing Risk

Starting a chainsaw can be dangerous if not done correctly. Here’s a safe starting procedure for the MS391:

Placement: Place the saw on a firm, level surface.
Choke: Engage the choke (usually by pushing the choke lever all the way out).
Starting Grip: Place your left hand firmly on the front handle and your right foot through the rear handle to secure the saw.
Pull Start: Pull the starter cord with a smooth, controlled motion. Avoid yanking the cord.
Warm-up: Once the engine starts, disengage the choke gradually.

Safety First: Always wear appropriate personal protective equipment (PPE), including gloves, eye protection, hearing protection, and chainsaw chaps.

My Experience: I once started a chainsaw without properly securing it, resulting in the saw kicking back and nearly hitting my leg. This close call reinforced the importance of following safe starting procedures.

Pro Tip 6: Mastering Felling Techniques for Efficient Wood Processing

Felling trees safely and efficiently is a crucial skill for wood processing.

Planning: Assess the tree for lean, wind direction, and obstacles. Plan your escape route.
Notches: Cut a notch on the side of the tree in the direction you want it to fall. The notch should be about 1/3 of the tree’s diameter.
Back Cut: Cut a back cut on the opposite side of the tree, slightly above the notch. Leave a hinge of wood to control the fall.
Wedges: Use felling wedges to help direct the fall and prevent the bar from getting pinched.

Important Note: Felling trees can be dangerous. If you are not experienced, seek professional training.

Case Study: In a study of logging accidents, improper felling techniques were found to be a contributing factor in over 60% of incidents.

Pro Tip 7: Efficient Bucking and Splitting Techniques

Once the tree is felled, the next step is bucking (cutting the tree into manageable lengths) and splitting.

Bucking: Use a sawhorse to support the log while bucking. Cut from the top down, avoiding pinching the bar.
Splitting: Use a maul or hydraulic splitter to split the wood. Split along the grain, avoiding knots.
Stacking: Stack the firewood neatly to promote air circulation and drying.

Comparison: Manual splitters are cheaper and require more physical effort. Hydraulic splitters are more expensive but significantly reduce the physical strain.

Actionable Advice: For large volumes of firewood, a hydraulic splitter is a worthwhile investment.

Wood Anatomy and Properties: The Foundation of Efficient Wood Processing

Understanding the anatomy and properties of wood is crucial for optimizing your wood processing techniques. Different wood species have different densities, moisture contents, and splitting characteristics.

Hardwood vs. Softwood

Hardwoods: Generally denser and more difficult to split than softwoods. They also tend to burn longer and produce more heat. Examples include oak, maple, and ash.
Softwoods: Generally less dense and easier to split than hardwoods. They tend to burn faster and produce less heat. Examples include pine, fir, and spruce.

Data Point: Oak firewood has a higher BTU (British Thermal Unit) rating than pine firewood, meaning it produces more heat per unit volume.

Moisture Content and Seasoning

Freshly cut wood: Can have a moisture content of 50% or higher.
Seasoned wood: Has a moisture content of 20% or lower.

Seasoning wood involves allowing it to dry, which improves its burning characteristics and reduces smoke production.

The Process:

Split the wood: Splitting increases the surface area for drying.
Stack the wood: Stack the wood in a well-ventilated area, off the ground.
Allow time to dry: Seasoning typically takes 6-12 months, depending on the species and climate.

Unique Insight: A moisture meter can be used to accurately measure the moisture content of wood.

Logging Tool Selection and Maintenance Best Practices

Beyond the MS391, several other logging tools can enhance your wood processing efficiency.

Axes and Mauls: For splitting wood manually.
Wedges: For felling trees and splitting stubborn logs.
Saws: Bow saws and crosscut saws for manual cutting.
Hydraulic Splitters: For splitting large volumes of wood.
Skidding Winches: For moving logs.

Maintenance Best Practices:

Clean tools regularly: Remove dirt and debris.
Sharpen tools: Keep cutting edges sharp.
Lubricate moving parts: Prevent rust and corrosion.
Store tools properly: Protect them from the elements.

Firewood Seasoning Techniques and Safety Considerations

Seasoning firewood properly is crucial for efficient burning and reducing creosote buildup in your chimney.

Seasoning Techniques

Stacking: Stack the wood in a single row, allowing for air circulation.
Covering: Cover the top of the woodpile to protect it from rain and snow.
Location: Choose a sunny, well-ventilated location.

Safety Considerations

Wear gloves: Protect your hands from splinters.
Wear eye protection: Protect your eyes from flying debris.
Use proper lifting techniques: Avoid back injuries.
Be aware of your surroundings: Watch out for hazards such as uneven ground and falling branches.

Project Planning and Execution: A Step-by-Step Guide

Effective project planning is essential for successful wood processing.

Assess the Task: Determine the volume of wood to be processed and the available resources.
Gather Equipment: Ensure you have all the necessary tools and equipment.
Plan the Layout: Designate areas for felling, bucking, splitting, and stacking.
Establish Safety Procedures: Review safety protocols and ensure everyone is aware of them.
Execute the Project: Follow the plan, taking breaks as needed.
Clean Up: Remove debris and store tools properly.

Real-World Example: I once underestimated the time required to process a large pile of firewood. As a result, I had to work long hours in inclement weather to finish the job. This experience taught me the importance of realistic planning and scheduling.

Conclusion: Maximizing Your Wood Processing Potential with the MS391

The Stihl MS391 is a versatile and reliable chainsaw that, when properly maintained and used, can significantly enhance your wood processing efficiency. By mastering the art of chain selection, optimizing carburetor tuning, practicing diligent bar and chain maintenance, using the correct fuel and oil, following safe starting procedures, mastering felling techniques, and employing efficient bucking and splitting techniques, you can unlock the full potential of this powerful tool. Remember to prioritize safety and plan your projects carefully to ensure a successful and enjoyable wood processing experience. Now, go forth and conquer those logs!

Next Steps:

Review your chainsaw maintenance routine.
Consider investing in a chain sharpening kit.
Practice safe starting procedures.
Plan your next wood processing project.

MS391 Specs Guide (7 Pro Tips for Optimal Wood Processing)