Husqvarna 120 Mark II Chain: Size, Part Number and Fitting

Check your bar first: 14”, 16” or 18”

Husqvarna’s current manual for the 120 Mark II approves three bars: 14”, 16” and 18”. All three take the same kind of chain, 3/8” pitch and .050” gauge. Only the loop length changes: 52 drive links on the 14” bar, 56 on the 16” and 62 on the 18” (manual p. 19). The saw’s standard bar is 14” or 16”. The 18” is the longest Husqvarna recommends (p. 18).

Husqvarna calls this pitch 3/8” mini. Other chain makers call it 3/8” low profile. Full-size 3/8” chain is a different size, and the manual does not list it for this saw.

Watch the link count on the 16” bar. Husqvarna sells its 16” S93G chain in 55 and 56 drive links. The 120 Mark II manual lists 56. The S93G part number ends in the link count: 585 42 21-56 is the 56-link loop.

The .325” question

The technical data in the same manual lists two pitches, .325” and 3/8”, and a 7-tooth sprocket for .325” next to the 6-tooth one for 3/8” (pp. 18–19). The approved bar-and-chain table, though, lists only 3/8” bars. Husqvarna’s earlier US/Canada manual from 2020 also listed two .325” bars with H30 chain: 13” with 56 drive links and 15” with 64 (p. 28).

That matters because a 56-link count alone does not tell you which chain you need. A 13” .325” chain and a 16” 3/8” mini chain both have 56 drive links. Check the old chain’s box or the bar’s markings for the pitch before you order, not just the link count.

Changing the chain

This is a gas saw. The bar is held by bar nuts under the sprocket cover, and a tensioning screw moves the bar forward. The manual’s steps (p. 12):

1. Pull the spark plug cap off the spark plug so the engine can’t start.
2. Remove the bar nuts and the sprocket cover.
3. Put the bar over the bar bolts and push it back as far as it goes.
4. Put on chainsaw gloves. Lift the chain over the drive sprocket and into the bar groove, starting on the top edge of the bar.
5. Make sure the cutting edges on the top of the bar face forward.
6. Refit the sprocket cover and guide the chain adjuster pin into the hole in the bar.
7. Check that the drive links sit on the drive sprocket and in the bar groove.
8. Tighten the bar nuts with your fingers.
9. Turn the chain tensioning screw clockwise with the combination wrench until the chain no longer sags under the bar but still turns easily by hand.
10. Hold up the bar nose and tighten the bar nuts with the wrench.

If the cover came off while the chain brake was engaged, the brake has to be reset before the cover will go back on. The manual shows how to do this with the bar tool, and warns that the brake spring is under tension (p. 12).

Setting tension

The chain tensioner on the 120 Mark II is a screw beside the bar, turned with the combination wrench (manual Fig. 40). A new chain stretches while it runs in, so check it often at first. The manual’s steps (p. 17):

1. Loosen the bar nuts with the combination wrench.
2. Tighten them again by hand, as tight as you can.
3. Lift the nose of the bar and turn the tensioning screw until the chain no longer hangs down from the bottom of the bar.
4. Keep the nose lifted while you tighten the bar nuts with the wrench.
5. Check that you can pull the chain round freely by hand and that it does not sag.

When a new chain doesn’t fix it

Husqvarna’s manual gives no measured wear limit for the sprocket or the bar on this saw. It asks you to do these checks instead (pp. 15–17):

• Drive sprocket: check it daily for excessive wear and replace it if needed. The 120 Mark II uses a spur sprocket, 6-tooth for 3/8” chain.
• Bar: turn the bar over every day so it wears evenly, keep the groove and the oil hole clean, and file off burrs from the bar edges every week.
• Oiling: if no line of oil shows when you run the saw with the nose pointed at a light surface, clean the oil channel and groove in the bar and check that the nose sprocket turns freely. If that doesn’t help, see a dealer.
• The chain itself: it is worn out when the cutting teeth are filed down to 4 mm (5/32”) long (p. 16).

Sharpening

Both approved chains, S93G and H37, take a 5/32” (4.0 mm) round file at a 30° filing angle. Set the depth gauges to .025” (0.65 mm) with a flat file and a depth gauge tool (p. 19). Husqvarna’s file gauge is 587 80 90-01 for S93G and 579 65 36-01 for H37.

The manual says to tension the chain before you file, since a slack chain moves sideways. File all the teeth on one side first, from the inside face of each cutter, with less pressure on the return stroke. Then turn the saw over and do the other side. Keep all the teeth the same length (p. 16). Sharpen the cutters first and adjust the depth gauges after.

If your saw has one of the older .325” bars with H30 chain, the 2020 manual lists a 3/16” (4.8 mm) round file for it instead (p. 29).