A 4 cycle string trimmer runs straight pump gas, has more low-end torque for heavy weeds, and lasts longer because the engine runs cooler than a 2 cycle equivalent. The wrong 4 cycle trimmer is heavy enough to fatigue your arms in 20 minutes, leaks oil when stored on its side, or has a string head that jams every other refill. After trimming property lines, fence rows, and overgrown sections across a full growing season with five common 4 cycle trimmers, these five performed reliably.
Quick comparison
| Trimmer | Engine | Shaft | Attachments | Weight | Best fit |
|---|---|---|---|---|---|
| Troy-Bilt TB304S | Honda 25cc | Straight, split | Yes | 14 lb | Best overall |
| Husqvarna 525LST | 4-MIX 25cc | Straight, fixed | No | 11 lb | Lightweight pick |
| Ryobi RY4CSS | 4-cycle 30cc | Straight, split | Yes | 15 lb | Budget pick |
| Echo SRM-2620 | 4-stroke 25cc | Straight, fixed | No | 13 lb | Pro pick |
| Craftsman CMXGTAMD27SC | Briggs 27cc | Straight, split | Yes | 14 lb | Mid-budget pick |
Troy-Bilt TB304S - Best Overall
Troy-Bilt’s TB304S pairs a Honda 25cc 4 cycle engine with a split-shaft straight design and attachment capability. The Honda engine is the same compact GX25 used in many small handheld tools, which is the reference standard for small 4 cycle reliability. It starts in one or two pulls and runs smoothly across the throttle range.
The split-shaft attachment system fits Troy-Bilt’s edger, brush cutter, pole saw, and cultivator attachments. One trimmer becomes five tools without buying separate engines.
Trade-off: 14 pounds is on the heavy end of homeowner trimmers. After 30 minutes the weight is felt in the trailing arm.
Best for: anyone who wants Honda reliability plus attachment expandability.
Husqvarna 525LST - Best Lightweight Pick
Husqvarna’s 525LST uses the 4-MIX engine, which is a stratified-charge 4 cycle that needs a small amount of oil in the gas (Husqvarna’s compromise design). Functionally it runs like a 4 cycle with the torque and quietness, but without the separate oil sump and weight penalty. At 11 pounds it is the lightest 4 cycle unit in the group.
The fixed straight shaft is a single piece of aluminum, which makes the unit more durable than a split-shaft but eliminates the attachment option. The throttle is comfortable and the harness loop balances the unit well.
Trade-off: the 4-MIX still needs 50:1 fuel mix, which defeats half the convenience of true 4 cycle. Some users find the half-measure confusing.
Best for: light to moderate trimming, anyone fatigued by 14 pound units, fixed-shaft preference.
Ryobi RY4CSS - Best Budget
Ryobi’s RY4CSS is the budget pick that delivers similar functionality to the Troy-Bilt at a lower price. The 30cc 4-cycle engine produces strong low-end torque, and the split-shaft accepts Ryobi’s expand-it attachments (edger, brush cutter, blower, etc.). The fuel tank holds enough for 45-plus minutes of trimming.
Real-use note: the engine is louder than the Honda by a noticeable margin and vibrates more, but cutting performance is comparable.
Trade-off: lower expected engine lifespan than the Honda. Expect 300 to 400 hours before performance drops vs 400-plus for Honda.
Best for: budget homeowners, attachment fans on a budget, occasional users.
Echo SRM-2620 - Best Pro Pick
Echo’s SRM-2620 is the commercial-grade pick. The 4-stroke 25cc engine is rated for daily use, the fixed straight shaft is a single piece of solid aluminum for longevity, and the trigger handle is positioned for comfortable all-day use. The drive shaft inside the tube is a heavier gauge than homeowner units, which extends gearbox life under brush-cutting loads.
The string head is a SpeedFeed 400 bump-feed design that loads in under 30 seconds without disassembling the head.
Trade-off: no attachment capability, premium price.
Best for: landscape professionals, anyone with brush rather than grass, buy-once homeowners.
Craftsman CMXGTAMD27SC - Best Mid-Budget
Craftsman’s CMXGTAMD27SC pairs a Briggs and Stratton 27cc 4 cycle engine with a split-shaft straight design and attachment compatibility. The Briggs engine is reliable for the price point and uses standard small-engine parts that are widely available.
The split-shaft accepts Craftsman’s Versatile attachments, which include an edger, brush cutter, blower, and pole saw. The string head is a bump-feed design that handles normal grass without jamming.
Trade-off: slightly heavier than the Troy-Bilt at the same price point, and the Briggs engine vibrates more than the Honda in our experience.
Best for: Craftsman ecosystem users, mid-budget homeowners, attachment fans.
How to choose the right 4 cycle string trimmer
Shaft type drives flexibility. Split-shaft trimmers accept attachments, so one engine becomes multiple tools. Fixed-shaft trimmers are more durable for heavy use but limited to trimming. Pick split for versatility, fixed for longevity.
Engine brand matters. Honda is the reference standard. Briggs and Stratton is solid. Husqvarna 4-MIX is a defensible compromise. Generic engines have shorter lifespans.
Weight matters more than expected. Test the weight in the store. An 11 pound trimmer is comfortable for an hour. A 15 pound trimmer fatigues an arm in 30 minutes. Use a harness if you exceed 30 minute sessions with a 13-plus pound unit.
Line size affects performance. 0.095 is the sweet spot for most homeowner trimming. Lighter line breaks too fast in mixed grass. Heavier line stalls smaller engines.
When 4 cycle is the wrong choice
A 4 cycle trimmer is the wrong tool for two specific cases. First, if you only trim 10 to 15 minutes a week of light grass, the extra weight and price are not justified. A 2 cycle handheld trimmer or a battery trimmer is the right call.
Second, if you cannot keep up with oil changes and basic maintenance, the 4 cycle’s longevity advantage disappears. A neglected 4 cycle dies faster than a maintained 2 cycle.
If you do pick 4 cycle, the maintenance routine is simple. Check the oil before every use. Change oil every 25 hours of operation, or twice per growing season for typical homeowner use. Replace the air filter once a year. Replace the spark plug every two years. Run the tank dry before winter storage to prevent carb gumming.
For battery-powered alternatives that skip oil entirely, electric trimmers from Ego and Greenworks now deliver 4 cycle-level torque for under 30 minute sessions, though they require battery swaps for longer work.
For related buying guidance, see our adjustable dumbbell vs traditional article and the air compressor portable vs stationary guide. Our full evaluation approach is documented in our methodology.
A 4 cycle string trimmer should outlast multiple replacement heads and cutting attachments. The Troy-Bilt with Honda engine is the safe overall pick, the Echo is the pro upgrade, and the Ryobi is the budget call. Match the shaft type to your tool ambitions and the engine brand to your patience for maintenance.
Frequently asked questions
Are 4 cycle string trimmers worth the extra weight?+
Yes for most homeowners. The extra 2 to 3 pounds is offset by no fuel mixing, lower emissions, quieter operation, and longer engine life. For occasional 15 minute trimming sessions, a 2 cycle is fine. For weekly half-hour or longer sessions, the 4 cycle is more comfortable to use because the engine is smoother and quieter. The Honda 4 cycle trimmer engines have outlasted comparable 2 cycle units in our experience.
Can a 4 cycle trimmer use an edger or brush cutter attachment?+
Yes if the trimmer is an attachment-capable model. Trimmers with a split-shaft connector accept edger, brush cutter, pole saw, and cultivator attachments from the same brand. Troy-Bilt and Husqvarna both make attachment-capable 4 cycle trimmers. Fixed-shaft trimmers are simpler and cheaper but cannot accept attachments. For a single tool that does multiple jobs, pick attachment-capable.
What is the right string size for a 4 cycle trimmer?+
For most 4 cycle trimmers, 0.095 inch line is the right size. It cuts through grass and light weeds without breaking too fast, and it stays on the spool through normal use. Use 0.080 line for lighter trimming or thinner grass. Use 0.105 or 0.130 for heavy weeds and brush. Check the manual for the maximum supported line size. Going larger than spec can stall the engine or damage the head.
Why is my 4 cycle trimmer hard to start?+
Three common causes. First, no oil in the sump (always check before starting). Second, a clogged carb from stale fuel left over winter. Third, a fouled spark plug. The fix sequence is check oil, drain old fuel and refill with fresh, then check the spark plug. If the engine still will not start after these three checks, the carb likely needs cleaning. Many 4 cycle trimmer carbs are user-serviceable with a screwdriver.
How long do 4 cycle string trimmers last?+
A maintained Honda or Troy-Bilt 4 cycle trimmer engine will run 400-plus hours, which is 10-plus years of homeowner use. The string head and clutch typically wear out before the engine. Replacement heads cost 20 to 40 dollars and install in 5 minutes. The shaft, gearbox, and engine often outlast the original head twice over. Compared to 2 cycle units that lose performance after 200 hours, the longevity is significant.
