The Stihl MS170 is one of the most popular entry level chainsaws in the world, valued for its light weight and maneuverability. However, when it comes time to buy a replacement chain, many owners are met with a confusing string of numbers such as 3/8 inch LP, 0.043, and 50DL. Selecting the wrong size is not just a matter of the chain not fitting, it can lead to dangerous equipment failure or permanent damage to your guide bar and drive sprocket. Understanding these three critical measurements, pitch, gauge, and drive link count, is the only way to ensure your saw remains safe and efficient. This guide will break down each specification and show you how to find the perfect Trilink or Stens replacement chain for your specific setup.
Understanding Chain Pitch
Pitch is perhaps the most fundamental measurement of a chainsaw chain. It refers to the average distance between the rivets that hold the chain together. To calculate the pitch, you would measure the distance between any three consecutive rivets and then divide that number by two. However, you do not need to perform math in the yard to find this information, as it is standard across most Stihl MS170 configurations.
The Stihl MS170 almost exclusively uses a 3/8 inch Low Profile pitch, often abbreviated as 3/8 inch LP or 3/8 inch Picco. It is important to note:
- 3/8 inch Low Profile is not the same as a standard 3/8 inch professional chain.
- The Low Profile design is specifically engineered for smaller, less powerful engines like the one in the MS170.
- Using a standard 3/8 inch chain on an MS170 will overwhelm the engine and will not fit the drive sprocket.
- The pitch of your chain must match the pitch of your drive sprocket and the nose sprocket of your guide bar.
If you attempt to run a chain with a different pitch, the teeth will not align with the sprocket, causing the chain to bind or jump off the bar immediately upon starting the saw.
Identifying the Correct Gauge
While pitch determines the length of the links, the gauge refers to the thickness of the drive links, which are the triangular parts of the chain that sit inside the groove of the guide bar. This measurement is critical because the chain needs to fit snugly enough to stay upright but loosely enough to slide freely without excessive friction.
For the Stihl MS170, there are two common gauges you will encounter depending on the bar that is currently installed on your saw:
- 0.043 inch Gauge: This is the most common size for the MS170. It is a "narrow kerf" design that removes less wood, making it easier for the small engine to maintain speed.
- 0.050 inch Gauge: Some owners or shops upgrade to a 0.050 inch bar for added durability. This gauge is slightly thicker and is a standard across many other small chainsaw brands.
- Using a 0.043 chain in a 0.050 bar will cause the chain to lean, leading to crooked cuts.
- Using a 0.050 chain in a 0.043 bar is impossible, as the drive links will be too thick to enter the bar groove.
High quality aftermarket brands like Stens and Trilink offer both gauges, so it is vital to check the stamping on your guide bar to see which one you require before ordering from xtremeope.com.
Counting the Drive Links
The final piece of the puzzle is the drive link count, often noted as "DL" on the packaging. This is the only way to determine the physical length of the chain. Unlike a bicycle chain, you cannot simply measure a chainsaw chain in inches with a tape measure because the tensioning system requires a precise number of links to function correctly.
To find your drive link count, you should remove the chain from the saw and count each individual drive link (the teeth that point inward toward the bar). For the Stihl MS170, the drive link count is determined by the length of the bar you are using:
- A 12 inch bar typically requires a 44 drive link chain.
- A 14 inch bar typically requires a 50 drive link chain.
- A 16 inch bar typically requires a 55 drive link chain.
Be aware that these numbers can occasionally vary by one or two links depending on the specific brand of guide bar used. Always count the links on your old chain to be 100 percent certain of the length you need. If you buy a chain with 52 links for a bar that requires 50, the tensioner will not be able to pull the slack out, making the saw unsafe to use.
Where to Find the Specifications
If you are unsure of your chain's dimensions, you do not always have to guess. Most manufacturers, including Stihl, stamp the specifications directly into the metal of the guide bar near the mounting slot. You may need to wipe away some oil or sawdust to see it, but you will usually find a small block of information that lists the bar length, the pitch, the gauge, and the drive link count.
If the stamping has worn off, you can cross-reference your saw model with the product listings on xtremeope.com. Premium brands like Trilink and Stens provide detailed fitment charts that allow you to select your MS170 and your bar length to find the exact matching chain. This takes the guesswork out of maintenance and ensures that when your new chain arrives, it is ready to be installed and put to work immediately.
Why Quality Aftermarket Chains are a Smart Choice
Once you know your pitch, gauge, and drive link count, you have access to a wide variety of high performance chains from Stens and Trilink. These brands are often preferred by DIYers because they provide professional grade cutting characteristics at a competitive price point.
Trilink chains, for example, often feature a low vibration design and chrome plated cutters that stay sharp longer than standard economy chains. Stens offers a range of safety chains that are specifically designed to reduce kickback, which is a major benefit for the occasional user of an MS170. By purchasing through Xtreme OPE, you are guaranteed to receive a chain that matches the technical specifications of your Stihl while providing the durability needed for tough property maintenance tasks.
Frequently Asked Questions
Can I put a longer bar and chain on my MS170? While you can physically fit a 16 inch bar on an MS170, it is generally recommended to stick to a 12 or 14 inch setup. The MS170 is a small displacement saw, and a longer chain creates more friction and weight, which can cause the engine to overheat and the oiler to struggle to provide enough lubrication.
What does "Narrow Kerf" mean? Narrow kerf refers to a thinner chain and bar combination, usually the 0.043 gauge. Because the chain is thinner, it removes a narrower slice of wood. This requires less power from the engine, allowing the saw to cut faster than it would with a standard thickness chain.
How do I know if my drive sprocket is worn out? Inspect the sprocket at the center of the clutch for deep grooves. If the chain has worn notches into the sprocket, it will no longer match the pitch of a new chain perfectly. This can cause a new chain to vibrate or wear out prematurely.
Is 3/8 inch the same as .325 pitch? No. These are two different sizes and are not interchangeable. The .325 pitch is common on mid sized saws like the Stihl MS250, while the 3/8 inch Low Profile is designed for smaller saws like your MS170.
Does the number of cutters matter as much as the drive links? When buying a replacement, the drive link count is the only number that ensures the chain will fit the bar. While the number of cutters affects how fast the saw cuts, it is determined by the chain's design and cannot be changed for a specific length.
Equip Your Stihl for Success
Navigating the world of chainsaw chain sizes does not have to be overwhelming. By focusing on the pitch, gauge, and drive link count, you can ensure that your Stihl MS170 is always equipped with the best possible cutting tool. A correctly sized chain provides the safest and most efficient cutting experience, allowing you to focus on the task at hand rather than struggling with your equipment. Whether you are looking for the precision of a Trilink chain or the reliability of a Stens replacement, having the right technical data is the first step toward a job well done. For all your Stihl MS170 needs and a wide variety of premium chains, visit the experts at XtremeOpe.com
Related Articles
- Why Chainsaw Chains Dull Quickly on a Stihl MS170 (And When It's Time for a Replacement) – Learn what causes chains to lose their edge quickly and how to maximize chain life.
- How to Tell When the Chain on Your Stihl MS170 Is Unsafe to Use – Identify the signs that your chain has become unsafe and should be replaced immediately.