What is A 2-Cycle vs 4-Cycle Weed Eater? [Benefits & Buying Guide]

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Back in the “old” days — before cell phones, excessive homework, and kids travel sports teams — weekends meant spending time at home with the family, cutting grass and pulling weeds to clean up the yard.

A string trimmer (i.e. weed eater) was the next best tool to the lawnmower itself. Move over handheld shears. These gas-powered marvels made the job of mowing, edging, and even putting in new flowerbeds easier than ever. 

Today, the same song has become even louder. Weed eaters are still the best products to rely on if you’re looking to clean up your sidewalk cracks, pathways, around trees, or just about anywhere in your yard. If you’re not using a string trimmer to keep your yard cleaned up, you’re simply doing it wrong! 

Now, with the rapid growth of technology, customers have discovered a noticeable upgrade in today’s string trimmers with relation to previous models.

While the previous versions relied on 2-cycle technology, today’s trimmers have advanced to 4-cycle technology, which comes with more benefits (and power) than its predecessor.

We’ll compare a 2-cycle vs 4-cycle weed eater so you can make the choice on which is the right equipment for keeping your lawn looking its best. 


How Do Both Engines Work?

Both the two-cycle and the four-cycle trimmers are very different in terms of operation. Other than the difference in the number of strokes, each of these engines come with separate features that we’re going to highlight in this section.

2-cycle engine

The two-stroke engine operates in two cycles to complete a single power cycle. While operating, this engine relies on up-and-down movements to power up. The first stroke involves sucking air into the system and exhausting out, while the second stroke involves combustion and applying the power.

When the piston moves to the top, both power and combustion happen, and when it reaches the bottom, air intake occurs, thus completing a single revolution. That’s all it takes to run a 2-cycle engine, in a nutshell. 

4-cycle engine

The four-cycle engine is quite similar to the two-cycle engine except that it adds two more steps to the equation. Each of the above aspects, instead of being combined as 2 and 2, gets its own step in the cycle.

The process of creating power in this type of engine involves power, exhaust, intake, and compression. This technique is also referred to as suck, squeeze, bang, and blow.

Four-stroke engines come with a crankcase and an oil distribution system that separates oil from gasoline for effective lubrication of the engine’s moving parts. Although the oil will need to be changed more often, these types of engines produce less exhaust and are quieter than two-cycle engines.


Comparison Between The 2-Stroke and 4-Stroke Engines

First, the 2-cycle weed eater doesn’t have any valves. Instead, it contains ports that exhaust fumes. On the other hand, a 4-cycle engine contains valves that dictate the opening, closing, intake, and exhaust operations.

A 2-cycle weed eater is easier to operate than a 4-cycle version because the engine doesn’t contain any valves that can make it heavier. These weed eaters are easier to operate although they typically lack enough power to tackle tough cutting tasks (think thick or wet weed clumps). 

On the other hand, a 4-cycle weed eater is bulkier (i.e. heavier) due to the four pistons, but the positive side is that they’re stronger and perfect for tackling bulky trimming assignments.

There is more wear and tear on the 2-stroke string trimmer compared to the 4-stroke version. This is because the two-cycle engine takes one power stroke to complete a revolution meaning more lubrication will be required.

On the other hand, the four-cycle version takes advantage of the available pistons to complete a revolution, thus resulting in less wear and tear overall.


Benefits of The 4-Cycle Weed Eaters


The two-cycle weed eater requires you to repeatedly pull a string to ignite the engine. On the other hand, a four-stroke engine has an improved state of technology that requires you to pull the string once to ignite the engine.

Easier Fueling

A four-stroke string trimmer uses standard gasoline, meaning you don’t need a separate can to mix the oil and gas together.

A two-stroke string trimmer, in comparison, requires you to pre-mix the gas and oil (somewhere between 50:1 to 20:1 depending on the specific motor and gas/oil used). 

Fuel Efficiency

You might think that a 2-stroke engine is more “efficient” on fuel since with dilution with oil, a standard gas can will last longer with use in this trimmer. You’d be wrong, though. 

The 4-stroke engines are actually more fuel-efficient; those valves actually help to add a boost to the power but without using more fuel to do so. Between a more efficient power source and reduced emissions, you actually have a cleaner, more fuel-efficient machine so you can stretch your gas dollars farther and refuel less often. 

Lower Emissions

As the world looks for ways of conserving the environment by restricting the use of gas-emitting engines, the four-stroke string trimmer is the perfect alternative that has already passed the CARB compliance test.

Unlike the two-stroke engine, the four-cycle engine used by most trimmers today has low gas emissions, which makes it environmentally friendly and the best to consider in most states across the globe.


Most commercial lawn care companies have continuously chosen the four-stroke string trimmer over the two-stroke version. This version is capable of handling more challenging cutting tasks and is relatively quiet compared to the two-stroke version. 

Ask any guy whose job it is to weed whack all day, and it’s an easy choice as to which trimmer he wants when noise is the biggest factor. 

With such a weed eater at the disposal, it becomes easier for you to trim your yard, pathways, or garden without waking your kids up or disturbing your neighbors.

More Power (Torque)

Four-stroke trimmers actually provide more power not in the engine itself but in the torque that it generates. This gives you much more whipping power to hack through weed clumps without breaking a sweat or bogging the machine down. 

Keep in mind that when comparing a 2-stroke vs 4-stroke with the same engine specs, the 2-stroke will complete more power strokes than the 4-cycle engine. So the extra power of the 4-stroke really is limited to the torque, not the raw engine power. Don’t be fooled on this aspect! 


Buying Guide:  How To Choose A 4-Cycle Weed Eater

As you’ve learned, there are definitely a lot of benefits to choosing a 4-stroke string trimmer over a 2-stroke. Where they do fall a little short is in having more parts to potentially repair if something breaks, being a bit heavier than a 2-stroke counterpart, and they do tend to cost more than a 2-stroke option. 

But all things considered, for the average homeowner a 4-stroke is the way to go.

  • You’ll stink up the yard less without that gassy smell as you work.
  • Your neighbors will thank you for using a quieter piece of equipment. 
  • You’ll be able to get the job done faster with that higher torque (and have more time to enjoy the back deck and watch your neighbors sweat over the same job). 
  • You’ll spend less time and make less mess by not having to mix gas. 

So once you’ve come to the 4-stroke decision, how do you choose which model is the right one for you? 

You’ll want to consider things like: 


You can choose between curved or straight, but straight will typically offer the most durability and often be more versatile (i.e. attachments potential). 

Curved will be easier on your back, however, since you essentially don’t need to hold the head out so far from your center of gravity. 


You can get some cheaper 4-stroke options for under $200, but you’ll get your best luck and overall performance with a machine that costs a little more (think $300+). 

That said if it’s not in the budget to get one of the bad boys, know that a cheaper option will still get the job done, although it may be slower (and with slightly less power) than the higher-end options. 


Not all weed eaters are made alike. Some offer attachments for edging or thicker brush, whereas many actually don’t. But if you’ve got a variety of terrain or trimming needs, buying a model with (or compatible with) attachments may be a better choice for you. 

Carry Method

Most homeowners go with those standard handheld string trimmers with a curved loop handle and a shaft grip.

There are, however, some pretty awesome backpack-style models out there. While typically only seen with landscape maintenance companies, some homeowners glow at the thought of weed eating the backyard almost in seconds with that kind of power, compared to walking around with a handheld trimmer. 

String Material

They’re called “string trimmers” for a reason — they’re equipped with a spool wound with thick plastic “string” that whips around at near 400+ mph to make short work out of weeds and tall grass. 

You can, however, choose to buy trimmer heads that can use plastic or metal blades that offer more long-lasting durability than string, although they’re less ideal around obstacles such as chain-link fences (can’t get in the openings well) or landscape blocks (may nick and damage both the block appearance as well as the blades). 



2-Cycle vs 4-Cycle Weed Eater FAQ

Does a 4-cycle weed eater need oil? 

Yes, it’s an engine, therefore it still needs to be lubricated. You’ll need oil in the engine itself, and it will need to be changed periodically, just like your car. Where you do NOT need oil, is mixed with the gas, however. 

Are 4-cycle weed eaters any good? 

Clearly! As mentioned above, while the raw power output in equally configured 2-stroke vs 4-stroke trimmers may be slightly less for the 4-cycle, the overall weed thrashing and smashing power is better on the 4-cycle weed eater, due to torque. 

Do 4-cycle string trimmers come in curved shaft and straight shaft models? 

Yes, you can find a model in either shaft configuration to best suit your needs and preferences. 

Can I use a 4-cycle weed eater as an edger? 

While not every string trimmer has (or fits) attachments like edger attachments, you can turn many of them around at a different angle to make it work as an edger. 

Do double check that a particular model won’t have any engine problems if it’s turned upside down, for example. 

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