Homelite ST-385 trimmer Parts

Most Homelite ST-385 trimmers run best with 0.080 inch (2.0 mm) trimmer line; if your cutting head is a lighter-duty style, 0.065 inch line is also common. Match the line size to your trimmer head so it feeds smoothly and does not overload the engine.

• Start with 0.080 inch line for general trimming and thicker weeds.
• Use 0.065 inch line if the head jams with thicker line or you mainly trim light grass.
• If the line will not feed, step down one size (for example, from 0.080 to 0.065).
• If the line breaks too easily, step up one size (only if the head accepts it).
• Replace worn head hardware so the line can advance correctly (for example, a missing fastener can let parts shift).

Using the correct diameter helps the ST-385 maintain RPM, reduces bogging, and prevents frequent line jams. Oversized line can strain the clutch and engine; undersized line can snap constantly and slow your work.

If the head is loose or misaligned, line feeding problems get worse. Check that fasteners are present and tight; a replacement like the screw 82540 can help restore proper fit if the original is stripped or missing.

Last updated: February 2026

For the Homelite ST-385 gas line trimmer, use fresh gasoline mixed with 2-cycle engine oil (a 2-stroke fuel mix). Mix only what you will use soon, and always use the exact gas-to-oil ratio listed for your engine to prevent hard starting, poor power, or engine damage.

• Use fresh, clean unleaded gasoline (stale fuel is a top cause of no-start issues).
• Use 2-cycle oil made for air-cooled small engines.
• Mix fuel in an approved fuel container; do not mix in the trimmer tank.
• Avoid fuel that has been sitting for more than 30 days (unless treated with stabilizer).
• Avoid “straight gas” (no oil) in a 2-cycle trimmer.

Your ST-385 may specify one of these common ratios; use the exact ratio for your engine.

• Shake the fuel can before filling so the oil stays evenly mixed.
• Fill on a cool engine and wipe up spills before starting.
• If the primer bulb is cracked or will not fill with fuel, replace it; see primer bulb UP04802.
• If the trimmer starts then dies, check for restricted fuel flow; a clogged tank filter is common; see filter 49422.

Correct 2-cycle fuel mix lubricates the engine. The wrong ratio (or old fuel) can cause scoring, loss of compression, plug fouling, and repeated no-start or stall complaints.

Last updated: February 2026

For the Homelite ST-385 gas line trimmer, use a 50:1 fuel mix ratio (50 parts gasoline to 1 part 2-cycle oil). Measure accurately and shake the fuel can well before filling the tank so the oil stays evenly mixed.

• Use fresh, unleaded gasoline in an approved fuel container.
• Use 2-cycle oil made for air-cooled, 2-stroke engines.
• Add some gasoline first, then add the measured oil, then top off with gasoline.
• Cap the container and shake thoroughly.
• Shake again each time before refueling.

A correct 50:1 mix protects the piston, piston ring, and crank bearings from overheating and scoring. Too little oil can cause rapid engine wear; too much oil can foul the spark plug and increase smoke and carbon buildup.

Check these common fuel-related items:

• Old fuel (drain and replace with fresh 50:1 mix)
• Dirty fuel filter (replace the in-tank filter 49422)
• Cracked or stiff primer bulb (replace the primer bulb UP04802)
• Clogged muffler baffle (inspect and clean or replace the baffle muffler 04790)

Last updated: February 2026