Whether you're bucking logs or trimming bushes, the proper chain tightness is essential for safe and efficient cutting. Always adjust the chain prior to cutting to maximize your saw's cutting ability. Proper tension on the chain will also increase its life span.
Turn off the chain saw. Unlock the chain brake by pulling back on it. The chain brake is the plastic handle located on the topside of the saw's body, in between the bar and the throttle. With a gloved hand, spin the chain to ensure that the chain brake is off.
With gloved hands, hold the chain saw with the bar up and the throttle on the ground. Loosen the bar's retaining nuts with the wrench until they are finger-tight. The retaining nuts are located on the bar's faceplate cover, opposite the muffler.
Use the screwdriver to loosen the bar's tensioner screw. This screw controls the chain's tightness. Look on the faceplate cover; you will see a small hole in the center. The tensioner screw is located just below that, inside the faceplate cover. You do not need to remove the faceplate cover to reach the screw. Stick the screwdriver in through the hole until it is connected to the tensioner screw.
To tighten the tensioner screw, turn it clockwise; to loosen the tensioner screw, turn it counter-clockwise. Pull down on the chain to make sure that it is properly tightened. There should be a finger's gap in between the bar and chain when the chain is pulled down.
Re-tighten the bar's retaining nuts with your hand. Then, use the wrench to ensure that the bolts are fastened tightly to the chain saw. With a gloved hand, spin the chain around the bar. The chain should glide smoothly.