Yard Machines Walk-Behind String Trimmer
Lawn · lawn
Wheeled walk-behind string trimmer powered by a 3.5 HP 4-stroke engine. Handles tall grass, rough fence lines, and overgrown areas that handheld trimmers can't reach in a single pass. Self-propelled wheel drive makes it manageable in thick growth. Runs on regular gasoline — no mixing required.
Quick Reference
- Make / Model: Yard Machines by MTD — 25A-201G352
- Serial Number: 1C290C90647
- Engine: 3.5 HP 4-stroke (regular gasoline, no mix)
- Cutting width: 18 inches
- Fuel: Premium 91
- Head type: No-feed string head
- Line size: 0.095-inch+
- Best for: Tall grass, rough fence lines, overgrown areas
Full Specs
Full machine and engine specifications.
Yard Machines Walk-Behind Trimmer — Machine Specs
| Spec | Value |
|---|---|
| Manufacturer | MTD Products Inc, Cleveland, Ohio 44136 |
| Brand | Yard Machines by MTD |
| Model number | 25A-201G352 |
| Serial number | 1C290C90647 |
| Cutting width | 18 inches |
| Engine output | 3.5 HP |
| Engine type | 4-stroke OHV (overhead valve) — no oil/gas mixing |
| Fuel | Regular unleaded gasoline, 87 octane minimum |
| Oil | SAE 30 motor oil (check dipstick before each use) |
| Drive | Wheeled self-propelled |
| Trimmer head | Bump-feed string head |
| Line size | 0.095-inch monofilament (company standard) |
| MTD customer support | 1-800-800-7310 / 1-330-220-4683 |
Fuel & Oil
4-stroke engine — runs on straight gasoline, not a fuel mix. Oil is separate and must be checked before every use.
- Fuel: regular unleaded gasoline, 87 octane minimum — NO oil added to the tank
- Oil: SAE 30 motor oil — check the dipstick before every use; top off if low
- Change oil after the first 5 hours of use (break-in change), then every 25 operating hours or each season
- Never run the engine with a low or empty oil level — 4-stroke engines will seize without lubrication
- Fill fuel tank when cool and on level ground; wipe any spills before starting
- Store with a full tank or fully drained — partial fuel left over winter causes gum and varnish buildup
Before Each Use
Pre-use check — 2 minutes before you pull the cord.
- Engine oil level at FULL on the dipstick — do not start a low-oil engine
- Fuel tank has sufficient regular gasoline — no oil added
- String head loaded with 0.095-inch line; check bump knob and line level
- All guards and shields in place and undamaged
- Wheels spin freely; wheel drive mechanism engages on handle squeeze
- Handle grip and bail bar secure — no cracks or loose hardware
- Clear the cutting zone — no bystanders within 30 feet before starting
Maintenance Schedule
4-stroke engines need regular oil and air filter service to stay reliable.
Service Schedule — Yard Machines Walk-Behind Trimmer
| Interval | Task |
|---|---|
| Before each use | Check engine oil level; inspect string line level; check guards |
| First 5 hours | Change engine oil (break-in service) |
| Every 25 hours / each season | Change engine oil with SAE 30; clean or replace air filter |
| Each season | Inspect spark plug — replace if fouled or worn; clean cooling fins |
| Each season | Check and lubricate wheel axles; inspect drive belt or cable |
| As needed | Replace 0.095-inch trimmer line; replace bump knob if cracked |
| End of season | Drain fuel or add fuel stabilizer; change oil; store clean and dry |
Troubleshooting
Common field issues and fixes.
Yard Machines Walk-Behind Trimmer — Field Troubleshooting
| Symptom | Likely Cause | Field Fix | Stop & Call Shop If |
|---|---|---|---|
| Engine won't start | Choke not set correctly, stale fuel, flooded, low oil shutoff triggered | Set choke to FULL for cold start; pull 3–4 times; if flooded, choke OFF and crank until it fires; check oil level | Still won't start after oil confirmed full and correct choke procedure — engine or ignition service |
| Engine starts but dies immediately | Choke moved too soon, carburetor dirty, fuel restriction | Let engine warm 30–60 sec before moving choke to RUN; check fuel flow from tank | Dies on every run after proper warm-up — carburetor needs service |
| Line won't feed when bumped | Line welded from heat, spool empty, bump knob spring worn | Pull spool, separate or replace line with 0.095-inch gauge; replace bump knob if not springing back | New spool still won't feed — head assembly needs replacement |
| Excessive vibration | Unbalanced or bent trimmer line, debris wrapped around head, worn bearings | Stop engine; clear all debris from head and shaft; check line for even length | Vibration persists after debris cleared — head or drive shaft bearing service |
| Engine runs rough / smokes | Incorrect fuel (gas+oil mix accidentally used), air filter clogged, spark plug fouled | Drain tank and refill with straight regular gasoline; clean or replace air filter | Smoke continues on fresh fuel with clean filter — engine service needed |