Echo CS-310 Chain: Size, Part Numbers and Fitting for the 12", 14" and 16" Bars

Check your bar first: 12”, 14” or 16”

Echo’s manual approves three bars for the CS-310 (p. 40). All three take the same 3/8” low-profile, .050” chain. Only the loop length changes:

Echo’s product page lists the saw with 14” and 16” bars, so most CS-310s you’ll find have one of those two. The 12” bar is an approved option in the manual and the parts catalog (p. 15).

The manual’s table gives the pitch as 3/8 in. Echo’s 91PX chain page spells it out: 3/8” low profile, .050” gauge. The manual also says the chain and bar gauge must match (p. 41).

To check yours, look at the part number stamped on the bar near the saw body, or read the old chain’s box. If neither is there, lay the chain flat and count the drive links, the teeth that ride in the bar groove.

Changing the chain

The CS-310 holds the bar with nuts on the sprocket guard and a side-access tensioner. Echo’s steps (manual pp. 23–24):

1. Release the cylinder cover latches and take off the cylinder cover. Pull the spark plug lead.
2. Remove the sprocket guard nuts and lift off the sprocket guard.
3. Take off the old bar and chain.
4. Unlock the chain brake. Fit the bar on the studs and slide it back toward the sprocket.
5. Fit the chain with the cutters on top of the bar facing forward, toward the nose.
6. Refit the sprocket guard over the studs. Make sure the tension adjuster pin goes into the adjuster hole in the bar. Run the nuts down finger tight.
7. Set the tension (below), then tighten the nuts to 20–23 N·m (175–200 lbf·in). Echo warns not to overtighten them.

Setting tension

Always loosen the sprocket guard nuts before you turn the adjuster. Turning it with the nuts tight can damage the guard and the tensioner (p. 24).

With the cylinder cover off and the plug lead pulled, unlock the chain brake and loosen the nuts. Hold the bar nose up and turn the adjuster screw clockwise until the chain touches the underside of the bar. Tighten the nuts with the nose still held up. Then pull the chain around the bar by hand. If you feel tight spots, back off the adjustment (p. 25).

Echo notes that all chains need frequent adjustment. Check tension often while you work and never run the saw with a loose chain (p. 35).

When a new chain doesn’t fix it

A worn sprocket wears a new chain fast. The CS-310 uses a 6-tooth spur sprocket, 3/8 in. pitch (p. 57). Echo says to check it every time you fit a new chain and to replace it once it has worn 0.5 mm (0.020 in.) or more (p. 48).

Echo’s manual gives no groove-depth limit for the bar. It says to clean the groove and oil holes, and to turn the bar over from time to time (p. 48). Also keep the bottom edge of each drive link sharp: the drive links clear sawdust out of the groove (p. 52).

Sharpening

Echo calls for a 5/32 in. round file plus a flat file (p. 52). Echo lists the same 5/32” file for its 91PX chain. Hold the file level and use a file holder to keep the angle. The manual’s figures show a 30° top plate filing angle and an 80° side plate angle, with about 1/5 of the file diameter above the cutter edge (pp. 52–53).

Set the depth gauges with Echo’s depth gauge tool and the flat file, to 0.64 mm (0.025 in.), and round off the front edge of each gauge. When you’re done, wash the filings off and oil the chain before you cut. Filings left in the groove wear the bar and chain early (p. 53).