Follow these easy steps to change the blade on a MS291 or MS271 Stihl chainsaw.

Tools and parts used:

Steps for Changing the Chain on a Stihl MS291 Chainsaw

  1. Remove the bar cover by removing the 2 nuts using a 3/4″ wrench
  2. Remove the bar and old chain
  3. Clean the oil and woodchip residue from the sprocket
  4. Turn the tensioner screw counter-clockwise to relax the tension pin
  5. Flip the bar over (change its orientation every time you change chains for even wear)
  6. Feed the new chain onto the bar – cutting surfaces should face out on top of the bar
  7. Place the bar and chain onto the saw, feeding the chain around the crank
  8. Make sure the tensioner pin is in appropriate hole in the bar
  9. While holding the bar and chain, tighten the tensioner screw until the chain is taught
  10. Put the bar cover back on and put the 2 nuts back on, tightening them finger tight
  11. Perform the final tension adjustment of the tensioner screw
  12. Fully tighten the cover nuts with the 3/4″ wrench
  13. Verify the proper tension (should be able to pull the chain ~ 1/4 to 1/2 inch from the bar

Alright, let’s go through each of these in a little more detail with pictures!

Step 1: Remove the Bar Cover

Use a 3/4″ wrench of the wrench tool that came with the saw.

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Loosen the two nuts holding the cover on.

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Remove both nuts.

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The sprocket, tensioner pin, and chain are visible.

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Step 2: Remove the Bar and Chain

Remove the bar and the old chain.

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This old chain had been sharpened quite a few times and was due for a change. The new chain is on the left, and the old chain is on the right in the picture below.

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Step 3: Clean Residue from the Sprocket

This is an excellent opportunity to clean the debris from the sprocket and bar studs.

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Here is a close-up view of the tensioning screw and tension pin.

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Step 4: Relax the Tensioner Screw

The old chain will likely have stretched, and the new chain will be shorter. Back up the tension pin by screwing the tensioning screw counter-clockwise.

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Step 5: Flip the Bar

It is a good idea to flip the bar everytime you change the chain in order for the bar to wear more evenly.

Step 6: Put on the New Chain

Take the new chain and line it up on the bar. Note that the cutting surfaces should face outward on the top of the bar, and in (toward the engine) on the bottom of the bar.

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Step 7: Place the Bar and Chain onto the Saw

While holding the chain on the bar, put the bar and chain back onto the saw. Loop the chain over the sprocket drive.

Step 8: Line Up Tension Pin

Make sure the tensioner screw is in the corresponding hole on the bar.

Step 9: Tighten the Tensioner Screw

While holding the bar and chain so that the bar does not come off the tension pin and the chain stays on the sprocket, use a flat-blade screwdriver to tighten the tensioner screw by turning it clockwise. Do not worry about getting it super tight. We will adjust the tension in a later step.

Step 10: Put the Cover Back On

While holding the bar and chain in place, fit the bar cover back on.

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Put the 2 nuts on and tighten them finger tight.

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Step 11: Adjust the Chain Tension

Using the flat-bladed screwdriver, tighten the tension by turning the screw clockwise.

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The proper tension is achieved when you pull on the chain and it comes away from the bar by about 1/4″ – 1/2″, or to where the drive links are just about to come out of the bar groove.

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Step 12: Fully Tighten the Cover Nuts

Fully tighten the cover nuts with the 3/4″ wrench.

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Step 13: Verify the Chain Tension

After tightening the cover nuts, verify once again the tension of the chain. Re-adjust if necessary.

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Conclusion

That’s about it. I hope this was helpful. This is the chain I use on my 18″ bar.

Here are a few more pictures showing the old and new chain side-by-side.

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Thanks for reading practicalmechanic.com!

Replacement Chainsaw Chain Options: