How to Tighten Chain on Stihl Chainsaw

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STIHL Instruction Manual

I'm Casey Kitz, and I'm Lou Cerella, and we're your hosts for the STIHL How-To Series.

STIHL created the How-To Series to give you some tips and general advice on how to operate and maintain your STIHL power tools. Of course, as always, STIHL recommends that you read and understand the information provided in the STIHL instruction manual that came with your STIHL product. If you can't locate your manual, it, along with all our instruction and safety manuals, can easily be viewed and downloaded for free from our website at STIHLUSA.com.

So what do you say, Lou? Let's get started.

STIHL Chain Tension

As you can see, Lou and I use our chainsaws quite a bit.

Yep, and one thing we have to pay close attention to is the tension of our saw chain. As the saw is being used, the chain will have a tendency to loosen up, so it's very important that we check our chain tension often.

Louie is right. Not only does a loose chain cause damage and premature wear to the chain itself, it also causes damage to the sprocket and the bar. So in this segment, Lou and I are going to show you how quick and easy it is to keep your chain properly adjusted.

Here we have a STIHL MS 271, what we call a side-access chain tensioner. This is where you insert your scrench or a flathead screwdriver to adjust the tension.

Wait a minute, Louie. I got a lot of people asking me, what is a scrench? Even my dad wanted to know.

It's simple. It's a tool with a screwdriver on one end to adjust chain tension. It's got openings on the other end to tighten the bar nuts, and sometimes even an opening to tighten the spark plug.

On this STIHL MS 170, the chain tensioner screw is located in the front of the saw. Sometimes the tensioner can be on the inboard side of the bar, and sometimes on the outboard side, depending on the chainsaw you have.

And this STIHL MS 211 C shows what STIHL refers to as their Quick Chain Adjuster. With this style, no tools are needed to make the adjustments.

With the side cover removed, you'll see the adjustment pin. This pin engages the bar and moves forward and backward depending on if you need to tighten or loosen the chain tension on the bar.

There are several openings. STIHL bars are designed so the bar can be mounted on either side. That's important because you want to turn the bar over to distribute the wear evenly on both sides, resulting in longer life of the bar. STIHL recommends that you do this every time you sharpen or replace the chain.

These small holes are where the bar and chain oil is channeled to the inside of the bar rails. This long groove is where the bar studs support the bar on the powerhead.

And this is the hole where the adjustment pin needs to line up. Anytime you loosen or remove the side cover, make sure the pin is aligned with the hole before you put the cover back on, or you can severely damage the saw.

Now, when installing or replacing the chain, it's easiest if you adjust the pin to the loosest position, or all the way back. Place the chain on the bar and then over the sprocket. Make sure the drive links fit correctly with the sprocket.

Position the bar where it fits securely on the bar studs and the adjustment pin is lined up with the proper hole in the bar. Double-check that the pin is aligned in the adjustment hole on the bar, and then place the side cover on the saw.

Tighten the nuts or the quick chain adjuster, depending on what style you have, but only hand-tight. You still want play up and down on the bar. If it's too tight, you won't be able to make the necessary adjustments.

Chain Tension Adjustment

Next, let's talk about chain tension adjustment. There are two different scenarios that we can consider: a cold chain that hasn't been run for a while, and a hot chain that has just been used.

First, the cold chain. Casey's going to loosen the bar nuts just enough so the bar has up-and-down play, and then he's going to start tensioning the chain by rotating the adjustment screw clockwise. He'll adjust it to where the chain tie straps just touch the bottom of the bar rail.

Now, this is really important. Bars have a slight amount of movement up and down, as Casey's showing you. To finish the adjustment process, you need to hold the tip of the bar up. When you do this, you'll see that the chain once again has slack in it.

While holding the tip of the bar up, continue to tighten the chain until it's snug against the bottom bar rail. Still holding the tip of the bar up, tighten the bar nuts, then pull down on the chain. It should snap back up to the bottom bar rail.

Next, with both hands, rotate the chain around the bar. It should move freely with little effort. If it doesn't, loosen the bar nuts and take a little tension off the chain, then tighten and repeat the process of checking the tension.

With a little practice, this will become very easy and instinctive. In the end, you'll want the chain to be snug on the bottom rail, but loose enough that it will rotate freely around the bar.

Chain Tension Adjustment After Cutting

So that's the procedure for adjusting a cold chain, one that hasn't been used. The adjustment for a chain that you just finished cutting with is a little different.

We've just finished cutting with the saw, and you can see the chain is hanging slightly below the bar rail, but the drive links are still well within the bar groove. This chain is hot and has stretched due to the heat. That's normal.

As a chain begins to cool down, you'll see how it tightens up again. So if you were to tighten this chain while it was hot, then stop work long enough for the chain to cool down, you'll end up with a chain that's overly tightened, and this could damage the saw.

In this case, where we've been using the saw and the chain is slightly loose, this is normal and you should continue using the saw as it is. But on the other hand, if it's loose enough where the drive links are close to coming out of the bar rail, as in this example, you should stop using the saw, let it cool down, and then readjust the chain.

And one last thing: when you're done working, loosen that chain. Storing a chainsaw with a tight chain can cause damage to the crankshaft and the bearings.

Now you know the proper way to adjust your chainsaw tension. This is Lou Cerella and Casey Kitz. See you next time.

Come on, Lou, let's go for some lunch.

Not until you fasten that seat belt, Casey.

You're always telling me what to do.

Come on, I'll buy this time. Maybe next time you let me drive.