How To Assemble the Bar and Chain on a Chainsaw

Brandon:
Today we’re going to walk through how to install the guide bar and chain on a Husqvarna 120 Mark II chainsaw.

Safety First

Before getting started, always follow proper safety steps:

• Disengage the chain brake.

• We’ve already removed the three screws on the top filter cover.

• To prevent accidental starting, disconnect the spark plug wire and set it aside.

• Put on protective gloves before handling the chain.

Step 1: Remove the Clutch Cover

• Loosen and remove the guide bar nuts.

• Remove the clutch cover and set it aside.

Step 2: Install the Guide Bar and Chain

1. Place the guide bar onto the posts and slide it back as far as possible.

2. Take your chainsaw chain, making sure the cutting teeth face in the correct direction.

3. Loop the chain around the clutch drum and onto the sprocket. Spin it slightly to ensure it’s seated correctly.

4. Fit the drive links into the guide bar groove. Roll the chain around the bar and sprocket, giving it another spin to double-check proper seating.

Step 3: Reattach the Clutch Cover

• Position the clutch cover back over the bar and chain.

• Make sure the tensioning screw post aligns properly with the slot on the guide bar—this is critical for proper adjustment.

• Hand-tighten the guide bar nuts onto the posts.

Step 4: Adjust the Chain Tension

• Use a scrench to lift the end of the guide bar slightly.

• Insert the scrench into the tensioning screw and turn clockwise to remove slack from the chain.

• Check that the chain moves freely along the guide bar without sagging.

Step 5: Final Tightening

• Once the chain is properly tensioned, fully tighten the guide bar nuts with the scrench.

• Spin the chain again to ensure smooth movement.

✅ Ready to Go

Your Husqvarna 120 Mark II chainsaw is now reassembled with the guide bar and chain properly installed, tensioned, and ready for use.