The primary difference between a two-stroke engine and a four-stroke engine is in how the oil and gas are delivered. In a two-stroke engine, the two are premixed and added as fuel. They are added separately in four-stroke engines.
Either model of engine is a good option for a weed eater, depending on what you want. In particular, if you want an engine that is lighter but louder, faster but more affordable a two-stroke engine is a good option. If you favor tools that are quieter but heavier, more dependable and cleaner and are okay with a little more expense a four-cycle engine is a good option.
They get their names from the number of total up-and-down cycles of the piston to complete power cycles. The two-cycle engine, with premixed gas and oil, requires two total up-and-down strokes to complete one power cycle during a crankshaft revolution. A four-cycle requires four total up-and-down strokes to complete two power cycles during a crankshaft revolution.
Four-cycle engines have more moving parts. Those additional parts add weight to it, so four-cycle engines tend to be heavier. They are also more costly. But because they also operate on twice the number of strokes, they are quieter and more efficient. They are also run more cleanly and spit out fewer noxious exhaust fumes.
Photo of Four-Cycle Weed Eater Engine
That makes them ideal for engines that you either have to move around on wheels or as a backpack. If you buy a weed eater with a four-cycle engine, you’ll want to make sure it’s equipped to fit onto your back to help manage the extra weight. That’s especially true if the lawn you’re trimming is pretty big.
Two-cycle engines, on the other hand, are lighter because they have fewer moving parts. Relative weight is a quality that makes them attractive as weed eaters, which as a rule are things you can move around quickly and cut through undergrowth with very little hassle. They are also, as a result of having fewer parts, more affordable.
On the downside, they operate less efficiently than four-cycle engines. That’s a result of them using fewer cycles per crankshaft revolution to generate power. Two-cycle engines also tend to be louder than four-cycle engines.
Photo of Two-Cycle Weed Eater Engine
In fact, it’s a good idea to run them as hard as possible, which means making them even louder, because they operate at their cleanest when they are run hard. They also generate a lot more horsepower at higher revolutions-per-minute than their four-cycle counterparts.
One thing you’ll want to keep in mind is that they also create a lot more exhaust fumes. This means operating in a messier environment. Make sure that you also check local and state air quality standards before you buy a two-cycle engine because they might be prohibited because of this.
Ultimately, your choice between a four-cycle engine and a two-cycle engine for your weed eater will come down to whether you want something that is quieter or something that offers more power. The quieter one, the four-cycle engine, will cost and weigh a little more. The more powerful one, the two-cycle engine, is louder and less efficient; but also a little easier on the wallet.
There is really no simple answer as to which kind of weed eater engine is better. Although there are nuances that might inform you that one kind is better for your yard, in reality it comes down to whether you want a weed eater so loud you think the world is coming to an end or one that puts out a lot of power.
Weed eaters with four-cycle engines are a little heavier and a little more expensive because they have more parts. They also go light on power. But, they’re quieter and in the long-run more dependable than two-cycle engine weed eaters, and in truth you just don’t really need that much power in a weed eater. If noise is a big deal for you, a four-cycle engine is probably where you want to start looking.
Two-cycle engine weed eaters are lighter, so they’re easier to carry around a big yard, and have a lot of power. But they’re loud, which can make simple yard maintenance an imposing chore. If you want lightweight power, a two-cycle weed eater is your best bet.
Hi there! My name is Adam and I write for HealthyHandyman. I have a great passion for writing about everything related to tools, home improvement, and DIY. In my spare time, I'm either fishing, playing the guitar, or spending quality time with my beloved wife. You'll also often find me in my workshop working on some new project!