A Stihl MS 250 chainsaw requires a specific chain. This chain must match the specifications of the bar, sprocket and chain. If an improper chain is used, serious injury can occur. Don’t use any chain other than what is recommended by Stihl. Pitch, gauge and length are all areas that need to be looked at before selecting the chain.
Select the proper pitch of the chain. The pitch of the chain tells the distance between any three rivets on the chain divided by two; rivets hold the teeth together. Stihl MS 250 chainsaws use pitches of 1/4, 3/8, .325 or .404 inches. The most commonly used chain, and the one that will give the best overall cutting performance, is .325 inches.
Determine the proper chain gauge. The gauge measures the thickness of the drive link and how it fits into the guide bar and sprocket. These measurements are set at an industry standard at .043, .05, .058 and .063 inches. This measurement must match the guide bar and sprocket you are using on your Stihl 250, which uses 12-, 14-, 16- or 18-inch bars. Choose the measurements that matches the size of the bar. Locate this number on the heel of the bar or in the package it came in.
Find the proper length of the chain. This measurement follows the same lengths as the guide bar. This measurement needs to match the length of the bar, because it needs to stay properly tensioned against the bar to cut through the wood.
Select a chainsaw chain with the proper kickback safety features. Kickback occurs when the chain binds under the cutting pressure and snaps, sometimes violently, backwards toward the operator. Choose only chains with low kickback design, which decreases the dangerous binding pressures and minimizes the risk of injury.