For most adults these days who grew up having their weekly chores consist of cutting the grass and whacking the weeds, the string trimmer they probably used was of the two-stroke variety, which required a gas and oil mixture to operate. Those same adults who browse big box and lawn equipment stores today will notice that there’s a new technology making waves in the industry, the advent and increasing popularity of 4-stroke string trimmers.
There’s a real big difference in 4-cycle and 2-cycle trimmers other than just the number of strokes it takes to make a cycle. It helps to understand how both motor types work in order to understand the features that make each desirable.
- 2-Cycle Engine. Defined by the fact that it only takes two up and down movements to complete a power cycle. Power is created in an engine when intake air is compressed and combusted into exhaust and a 2-cycle engine works with the end of the combustion stroke and the beginning of the compression stroke happening at the same time.
- 4-Cycle Engine. The 4-cycle engine does effectively the same thing as the 2-cycle engine, only with two more steps. The process of creating power in a 4-cycle engine goes 1) intake 2) compression 3) power 4) exhaust or as it’s more commonly known suck, squeeze, bang, and blow. Since each step is performed more concentrated 4-cycle engines often produce less exhaust and are much quieter.
Generally speaking, there’s less to a 2-cycle engine. Because of this the power to weight ratio can really be cranked up and most people who own a 2-stroke string trimmer will claim they can cut through every weed in their path and small trees in some cases.
Traditionally, a 4-stroke engine that had equal power as its 2-stroke counterpart would weigh too much for users who aren’t professional bodybuilders to maneuver with. That being said, advancing engine technologies as well as new lightweight shaft designs are enabling the 4-cycle trimmers to become a viable threat to take the throne as the most-popular weed whacker.
Benefits of 4-cycle weed eater
Besides 4-cycle trimmers already have benefits to consumers in these areas:
- Quieter. One of the hurdles that commercial lawncare companies often faced was if 4-cycle trimmers could handle the work load of the 2-cycle units that most workers probably had grown accustomed to dealing with. The truth is 4 stroke weed eater can easily handle common home weed whacking capabilities and do so at a much quieter rate, saving employees’ ears and avoiding rousing up and angering clients’ neighbors.
- Convenient. Since 4-cycle engines run on standard gasoline or diesel, they save the need of a separate can of gas for a mower in addition to a container of oil and a tank to keep the gas / oil mix separate as required for a 2-stroke trimmer to run. 4-cycle trimmers have also been known to start easier as they require less priming for the gas and oil to mix and often will fire up on the first pull of the starting cord.
- Lower Emissions. Having less exhaust is not only a luxury of a string trimmer, it’s becoming a law in more and more states. California string trimmers for instance have a mandatory law that they must be CARB compliant. The lower exhaust is positive in a number of ways from reducing the black fog inhaled, lowering a carbon-footprint on the environment, and not having clothes smell like exhaust.
Popular 4-cycle trimmers
There are a number of manufacturers either converting their whole product line over to 4-cycle trimmers or at least developing different types of hybrid models. Take a look at two of the most popular models to get a better overall feel of the 4-stroke evolution.
Poulan Pro 966774301 4-Cycle Gas Straight Shaft Trimmer
Poulan Pro is a manufacturer of commercial and residential heavy-duty lawn care equipment such as garden tractors, zero-turn mowers, push-mowers, tillers, and more. Their expanded product line also features chainsaws, snow throwers, leaf blowers, and of course hedge and string trimmers.
They are one of the few manufacturers that still produce both 2-cycle and 4-cycle weed whackers. The Poulan Pro 966774301 weed whacker model is powerful enough for commercial endeavors but still affordable as a spare home unit.
The first thing that consumers look for in a 4-cycle trimmer is if it will be able to handle the wear and tear of their individual yard. So long as a person doesn’t have to clear a number of ditches on their property, the 28cc engine of the 966774301 should have plenty of boost. The added engine power doesn’t make for an overtly heavy unit though, with the entire trimmer weighing a navigational 13 pounds, approximately. The head of the trimmer combs a 17″ wide maximum path which is about the industry standard.
As with string trimmers and almost every other lawncare product, value is switching more towards convenience of use instead of power or torque. This model follows that trend by offering a straight shaft design to alleviate bending and stooping for taller users.
Poulan Pro has also integrated their popular split boom shaft with Pro Link attachment system on this model. This feature enables users to quickly switch between attachments without an exorbitant amount of tools or extra pieces required.
Some attachments available that are sold separately include a blower, brush cutter, cultivator, pole pruner, and edger.
One more convenience of this model is the tap head system that feeds trimmer line on the go instead of having to stop and place pre-cut pieces of string in the unit.
What others are saying
For the most part, other online reviewers were ecstatic with their Poulan Pro 966774301 string trimmer. The most popular refrain was not having to mix gas and oil anymore as many people have damaged their trimmers in the pass by not getting the correct oil to gas ratio.
There were a few complaints about the carburetor being incorrectly calibrated for a certain climate but that’s a pretty easy fix.
Kawasaki KTFR27A Commercial String Trimmer
Most people are probably familiar with Kawasaki as a motorcycle manufacturer but the staple company is actually widely integrated within some of the most popular lawn products on the market today.
For instance, Kawasaki motors power mowers from Cub Cadet, Toro, Husqvarna, and Swisher to name a few. Kawasaki has put their own name on a few of their products, specifically a popular array of string trimmers such as the KTFR27A.
The Kawasaki KTFR27A has a unique design angle. The designers aimed to bring all the positive benefits of most 4-cycle engine trimmers (low emissions, quiet, convenient) while eliminating the most negative aspect – the weight. The result is a unit that weighs only 10 pounds, but since the engine casing is stripped down there is more reverberation and torque than one might expect. The 26cc engine provides plenty of power for even thick trimming jobs and the KTFR27A is rated for both commercial and residential uses.
The main selling point that Kawasaki goes with on this unit is the lightweight frame. That seems to be the most popular sentiment that other users agree set it apart from 4-stroke models of the same engine size and similarly priced 2-stroke trimmers.
Also like many other 4-cycle string trimmers on the market, the KTFR27A starts easy, usually on the first stroke. The first time a user runs the weed whacker will take some priming and competent handling of the enriching lever but the model is very stable after that. Taller users like the flex shaft on this particular Kawasaki unit but one thing it’s devout of is attachment capabilities, comparable to other units that offer blower, edger, or brush cutting capabilities in seconds.
What others are saying
Most other customer reviews always go back to the power to weight ratio offered in the Kawasaki KTFR27A and how convenient it is for users of all statures. Users have almost unanimously agreed that the trimmers start and prime very easily and for the most part repairs are accommodating.
Specifically the fuel line is very easy to replace (as they’ll all inevitably rot) compared to similar Husqvarna or Echo models. Some reviewers have complained that the model leaks fuel when it is stored upright and that they wish it held more line but those minor inconveniences can be offset by the lightweight design and 26cc cutting power.
The future of 4-cycle string trimmers
Most industry professionals would agree that 4-cycle engines are the future of string trimmers. Technologies will eventually fine tune these models to pack the same amount of power as a 2-stroke engine but without weighing a ton.
All that’s left for the consumer then is to find the features that work best for them. Some people like a straight shaft compared to a curved one depending on their body size and trimming needs. Likewise other consumers prefer the on-the-fly trimming speed of the tap-head line feeding system while others find the pre-cut string pieces more durable and convenient. Either way, finding the perfect string trimmer for one’s grounds is not just a stroke of luck anymore…it’s a science.