How to Adjust Chainsaw Tension

In order for a chainsaw to safely and effectively cut, its chain needs to have the proper tension around the metal bar upon which it rides. If the chain is too tight, not only will it rob the saw's engine of power due to increased friction, but the chain also runs the risk of breaking. If the chain is too loose, it can come off the bar and seriously injure the operator. And while some light-duty chainsaws feature automatic chain tensioning systems, most models require manual chain tension adjustment. Luckily, adjusting the tension on a chainsaw's chain is easy.

Perform a snap test

A quick way to measure the tension of a chainsaw chain is to perform what's known as a "snap test." To do this, start by disconnecting the chainsaw's spark plug lead. While holding the chainsaw in one hand, grasp the chain along the top center of the chainsaw's bar with two fingers of your other hand. (Always wear heavy gloves and protective eyewear when performing this test.) Lift the chain away from the bar and then quickly release it. A properly tensioned chain will rapidly snap back into position around the top of the bar and show no signs of sagging along the bottom of the bar. If the chain loosely falls into position along the top of the bar or sags along the bottom of the bar, it's a sure sign that the tension needs to be adjusted.

Adjust the bar

To increase the tension of the chain, the chainsaw's bar needs to be adjusted outward. Most chainsaws come with a combination wrench/screwdriver for this very purpose, and while variations of bar adjustment methods exist depending on the brand of chainsaw, most follow the same basic procedure:

• Set the chainsaw on a flat work surface.
• Disconnect the spark plug lead.
• Loosen the clutch cover nuts that hold the bar securely in place.
• While holding the nose of the bar up slightly, turn the chain tension screw clockwise until the slack is gone from the chain.
• (Most tension screws are located on either the front or side of the chainsaw body.)
• Tighten the clutch cover nuts.

It's important to note that the chain may need to be adjusted while in the middle of a day's work, so always bring the saw's combination adjusting tool along if you are working away from the house so that tension can be adjusted at any time. And of course, always follow any additional adjustment procedures as recommended in the chainsaw's operation manual.