Things You'll Need
Wrench
Screwdriver
Fuel pickup body
Hook
Unleaded gasoline
Stihl 50:1 two-stroke engine oil
Approved fuel container
Stihl BioPlus chain lubricant
The Stihl MS 270 chain saw is specifically designed to cut firewood around your house or out in the woods. The MS 270 features 2.5 kilowatts of power while only weighing about 12 pounds, which lets you tackle some fairly big jobs without killing your arms. Over time, you may start to experience some issues with your Stihl chain saw's operation but before you take it in for service, complete a few troubleshooting steps to see if you can correct the problem on your own.
Step 1
Turn off the chain saw. Once the blades stop moving, check the chain tension. If the chain is not snug against the underside of the bar or if the chain does not move when you pull it by hand, you need to adjust the tension. Remove the two nuts on the side of the machine, located just over where the bar extends from the motor, and then remove the plate those nuts were holding. Use a screwdriver to turn the screw clockwise to increase the tension, and counterclockwise to remove tension. Replace the plate and nuts when you are done.
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Step 2
Mix together 1 gallon of unleaded gasoline with 2.6 fluid ounces of Sithl 50:1 two-stroke oil in an approved container. Shake the container to mix up the solution.
Step 3
Tilt the chain saw onto its right side so that the fuel cap is pointing up. Flip up the handle located around the cap and then rotate it counterclockwise to remove it.
Step 4
Place a hook inside the fuel opening and grab the pickup body. Bring the pickup body out of the tank, pull it off of the hose and then push the new one in its place. Place the pickup body back into the tank, and then fill the tank with your gasoline and oil mixture. Replace and tighten the cap when you are done.
Step 5
Remove the oil filter cap from the chain saw. The cap is on the same side as the fuel cap, but on the end closest to the chain. Fill this tank with Stihl BioPlus chain and bar lubricant. Replace the cap when you are done.
Step 6
Tilt the chain saw upright again. Turn the knob located on the back of the motor counterclockwise, then lift up on the entire box covering the back of the motor. Clear any loose dirt located close to the air filter, then lift the filter up to remove it. Use your hand to remove any dirt from the filter and then replace it, but leave the cover off.
Step 7
Locate the spark plug just above the air filter and pull off its rubber boot. Turn the spark plug counterclockwise to remove it. Clean it off and ensure the gap between the electrodes at the end isn't too wide. The gap should be .5 millimeters, so if it is wider than that, push down on the bottom electrode until it is .5 mm away from the other electrode. Screw the spark plug back into place and replace the rubber boot.
Step 8
Locate the two or three screws on the right side of the air filter. Find the screw labeled "L" and rotate it clockwise until it stops, then turn it counterclockwise 1/4 turn. If your engine has three screws, now find the screw labeled "H." Rotate it counterclockwise for up to 3/4 of a turn, until it stops. This is the standard setting for the carburetor. You can adjust these screws, along with idling speed screw, while the motor is running to correct any issues with the chain speed. Replace the box over the back of the chain saw when you are done.
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