Stihl MS 251 Wood Boss Chain Size Guide (5 Expert Tips)

Let’s cut to the chase. You’re here because you want to make sure you’re running the right chain on your Stihl MS 251 Wood Boss chainsaw. You want to optimize its performance, maximize your cutting efficiency, and, most importantly, stay safe. You’re in the right place. I’ve spent years felling trees, bucking logs, and splitting firewood, and I’ve learned a thing or two about chainsaw chains along the way. This guide will give you the fast, practical answers you need, along with some expert tips to keep you cutting like a pro.

1. Understanding the Stihl MS 251 Wood Boss: A Chainsaw’s DNA

Before we dive into chain sizes, let’s understand what makes the Stihl MS 251 Wood Boss tick. This chainsaw is a popular choice for homeowners and professionals alike, striking a balance between power, weight, and affordability. It’s a versatile saw capable of handling a range of tasks, from limbing and pruning to felling small trees and bucking firewood.

The MS 251 typically comes with a 16-inch or 18-inch bar, but the optimal chain size depends on the specific bar length you have. This is crucial! Using the wrong chain can lead to poor performance, increased wear and tear on your saw, and even dangerous kickback.

Key Specs of the Stihl MS 251 Wood Boss:

Engine Displacement: 45.6 cc
Power Output: 2.3 kW (3.1 bhp)
Weight (without fuel, bar, and chain): 4.6 kg (10.1 lbs)
Recommended Bar Lengths: 16 in (40 cm) or 18 in (45 cm)
Chain Pitch: .325″
Chain Gauge: .063″ (1.6 mm)

Why These Specs Matter:

Chain Pitch: The pitch refers to the distance between any three consecutive rivets on the chain, divided by two. A .325″ pitch is common for mid-sized saws like the MS 251, offering a good balance of cutting speed and durability.
Chain Gauge: The gauge is the thickness of the drive links (the parts of the chain that fit into the groove of the bar). A .063″ gauge is standard for this saw. Using a chain with the wrong gauge will prevent it from fitting properly in the bar groove.

Personal Story: I remember once trying to use a chain with the wrong gauge on my old Stihl 026. The chain just wouldn’t sit right in the bar, and I spent a frustrating hour trying to figure out what was wrong. Eventually, I realized my mistake, and it was a valuable lesson learned! Always double-check your chain specs before you start.

2. Finding the Right Chain Length: Count Those Drive Links!

The most critical aspect of selecting the correct chain is ensuring it has the right number of drive links. This is what determines whether the chain will fit snugly and safely around the bar.

How to Determine the Correct Number of Drive Links:

Check Your Bar: Most chainsaw bars have the recommended chain size (specifically, the number of drive links) stamped directly on them. Look closely near the mounting point of the bar.
Consult Your Owner’s Manual: The owner’s manual for your Stihl MS 251 will provide the correct chain size for both the 16-inch and 18-inch bar options.
Count the Drive Links on Your Old Chain: If you have the old chain that fits properly, carefully count the number of drive links. This is the most reliable method.
Use a Chain Length Chart: Many online resources provide chain length charts based on bar length and chain pitch/gauge. However, these charts should be used as a guide only, and you should always double-check the number of drive links on your bar or in your owner’s manual.

Typical Chain Lengths for the Stihl MS 251:

16-inch Bar: Typically requires a chain with 55 drive links.
18-inch Bar: Typically requires a chain with 61 drive links.

Data Point: A survey of several online retailers and chainsaw parts suppliers confirmed that these drive link counts are the most common for the Stihl MS 251 with the specified bar lengths.

Warning: Never assume the chain length! Always verify the number of drive links before installing a new chain.

3. Chain Types: Choosing the Right Tool for the Job

Not all chainsaw chains are created equal. Different chain types are designed for different applications. Here’s a breakdown of the most common types you’ll encounter:

Full Chisel Chains: These chains have square-cornered cutters that provide the fastest and most efficient cutting in clean wood. They are ideal for professional loggers and experienced users who prioritize speed and efficiency. However, they are more prone to kickback and require more frequent sharpening.
Semi-Chisel Chains: These chains have rounded-corner cutters that are more forgiving and less prone to kickback than full chisel chains. They are a good all-around choice for homeowners and occasional users who need a balance of cutting speed and durability.
Low-Kickback Chains: These chains are designed with features that reduce the risk of kickback, such as bumper drive links or guard links. They are a good choice for inexperienced users or anyone who prioritizes safety.
Ripping Chains: These chains are designed for cutting wood along the grain, such as when milling lumber. They have a different cutter geometry than cross-cutting chains, which makes them more efficient for ripping.

Choosing the Right Chain for Your Needs:

For general-purpose cutting (firewood, limbing, small trees): A semi-chisel or low-kickback chain is a good choice.
For fast cutting in clean wood (professional logging): A full chisel chain is the best option.
For milling lumber: A ripping chain is essential.

Unique Insight: Many people underestimate the importance of using the right chain for the job. I’ve seen countless instances where someone struggled to cut through a log simply because they were using the wrong type of chain. It’s like trying to drive a nail with a screwdriver – it might work, but it’s not the right tool for the job!

4. Expert Tips for Chain Maintenance and Sharpening

A sharp chain is a safe chain. A dull chain requires more force to cut, which increases the risk of kickback and puts unnecessary strain on your saw. Regular chain maintenance is essential for optimal performance and safety.

Here are some expert tips for chain maintenance:

Sharpen Your Chain Regularly: The frequency of sharpening depends on the type of wood you’re cutting and how often you use your saw. As a general rule, sharpen your chain every time you refuel your saw.
Use the Correct File Size and Angle: Consult your owner’s manual or a chain sharpening guide to determine the correct file size and angle for your chain. Using the wrong file can damage the cutters and reduce the chain’s performance.
Maintain the Correct Depth Gauge Setting: The depth gauge is the small projection in front of each cutter. It controls the amount of wood the cutter takes with each pass. If the depth gauges are too high, the chain will cut slowly. If they are too low, the chain will be prone to kickback.
Clean Your Chain Regularly: Sawdust and pitch can build up on the chain and reduce its performance. Clean your chain regularly with a brush and solvent.
Lubricate Your Chain Properly: Proper lubrication is essential for reducing friction and wear on the chain and bar. Use a high-quality bar and chain oil and check the oil level frequently.

Data Point: Studies have shown that a sharp chain can reduce cutting time by up to 50% compared to a dull chain. This translates to significant time and energy savings, as well as reduced wear and tear on your saw.

Personal Experience: I once neglected to sharpen my chain for a long period, and I paid the price. I was struggling to cut through a relatively small log, and the saw was vibrating excessively. When I finally sharpened the chain, the difference was night and day. The saw cut through the log like butter, and the vibration was gone. It was a painful reminder of the importance of regular chain maintenance.

5. Safety First: Avoiding Kickback and Other Hazards

Chainsaw operation is inherently dangerous, and kickback is one of the most common and serious hazards. Kickback occurs when the upper tip of the bar contacts an object, causing the saw to suddenly and violently thrust back towards the operator.

Here are some tips for avoiding kickback:

Maintain a Firm Grip: Always hold the saw firmly with both hands.
Keep Your Body Balanced: Maintain a stable stance and avoid overreaching.
Be Aware of the Tip of the Bar: Avoid contacting the tip of the bar with objects, especially when limbing or cutting near the ground.
Use Low-Kickback Chains: As mentioned earlier, low-kickback chains are designed to reduce the risk of kickback.
Maintain Proper Chain Tension: A loose chain is more prone to kickback.
Never Cut Above Shoulder Height: Cutting above shoulder height increases the risk of losing control of the saw.
Wear Appropriate Safety Gear: Always wear safety glasses, hearing protection, gloves, and sturdy boots when operating a chainsaw.

Beyond Kickback: Other Safety Considerations:

Read Your Owner’s Manual: Familiarize yourself with the safety instructions and operating procedures outlined in your owner’s manual.
Inspect Your Saw Before Each Use: Check for loose parts, leaks, and other potential problems.
Never Operate a Chainsaw Under the Influence of Drugs or Alcohol: This should be obvious, but it’s worth stating.
Be Aware of Your Surroundings: Watch out for obstacles, power lines, and other hazards.
Use Proper Lifting Techniques: When handling logs or firewood, use proper lifting techniques to avoid back injuries.
Have a First-Aid Kit on Hand: Be prepared for minor injuries.

Case Study: I once witnessed a near-miss kickback incident while working with a fellow firewood cutter. He was limbing a tree when the tip of his bar contacted a small branch hidden beneath the leaves. The saw kicked back violently, narrowly missing his face. He was shaken but unharmed, and it served as a stark reminder of the importance of constant vigilance and proper technique.

Statistics: According to the Consumer Product Safety Commission (CPSC), chainsaws cause tens of thousands of injuries each year in the United States alone. Many of these injuries are preventable with proper training and safety precautions.

Actionable Takeaway: Take a chainsaw safety course! Many organizations offer courses that cover safe operating procedures, chain maintenance, and first aid. This is one of the best investments you can make in your safety and well-being.

Beyond the Basics: Advanced Wood Processing Techniques

Once you’ve mastered the fundamentals of chainsaw operation and chain maintenance, you can explore more advanced wood processing techniques.

Milling Lumber with a Chainsaw:

Milling lumber with a chainsaw is a challenging but rewarding process. It allows you to create custom lumber from logs that would otherwise be wasted.

Equipment: You’ll need a chainsaw mill attachment, which clamps onto your chainsaw bar and guides it along a straight line. You’ll also need a ripping chain, which is designed for cutting wood along the grain.
Wood Selection: Softwoods like pine and fir are easier to mill than hardwoods like oak and maple.
Safety Considerations: Milling lumber with a chainsaw is a strenuous and potentially dangerous activity. Wear appropriate safety gear and be aware of the risks of kickback and fatigue.

Creating Wood Art:

Chainsaws can also be used to create beautiful wood sculptures and carvings.

Equipment: You’ll need a chainsaw with a carving bar and chain, which is designed for precise cutting and detail work.
Wood Selection: Softwoods like basswood and butternut are ideal for carving.
Safety Considerations: Chainsaw carving requires a high level of skill and control. Start with simple projects and gradually work your way up to more complex designs.

Seasoning Firewood:

Properly seasoning firewood is essential for efficient burning and reduced creosote buildup in your chimney.

Wood Selection: Hardwoods like oak and maple are the best choices for firewood, as they burn hotter and longer than softwoods.
Processing: Split the firewood into manageable sizes and stack it in a well-ventilated area.
Seasoning Time: Allow the firewood to season for at least six months, and preferably a year or more.

Data Point: Seasoned firewood has a moisture content of 20% or less, while green firewood can have a moisture content of 50% or more. Burning seasoned firewood results in significantly higher heat output and reduced emissions.

Conclusion: Mastering Your Stihl MS 251 and the Art of Wood Processing

Choosing the right chain for your Stihl MS 251 Wood Boss is more than just a matter of matching numbers. It’s about understanding your saw, your needs, and the wood you’re working with. By following these expert tips, you can optimize your saw’s performance, improve your cutting efficiency, and, most importantly, stay safe.

Wood processing is a craft that requires knowledge, skill, and respect for the materials involved. Whether you’re felling trees, bucking logs, splitting firewood, or creating wood art, remember to prioritize safety, maintain your equipment properly, and always strive to learn and improve. The satisfaction of working with wood is immense, and the rewards of mastering these skills are well worth the effort. Now, get out there and make some sawdust! But do it safely!

Stihl MS 251 Wood Boss Chain Size Guide (5 Expert Tips)