Gas string trimmers are better at trimming tough weeds than most electric trimmers, but they're also louder and pollute more than electric string trimmers. Most are heavier and require more maintenance, too. The majority of gas trimmers have two-stroke engines. These trimmers cost less and weigh less than four-stroke models, and they are also easier to start. Their biggest drawback is that they run on a mixture of oil and gasoline, which does not burn cleanly. As a result, two-stroke gas trimmers are less efficient and more polluting than the four-stroke versions. For a great visual explanation of how two- and four-stroke engines work, we recommend visiting the excellent website, AnimatedEngines.com.
Among two-stroke trimmers, we found the best reviews overall for the Husqvarna 223L (*Est. $250) . This straight-shaft trimmer delivers plenty of muscle with its 24.5 cc engine and 17-inch cutting width. It weighs 9 pounds and uses a bump-feed spool that reviewers say works quite well. In a Popular Mechanics comparison test, the 223L earns praise for its power, easy start and minimal vibration. It earns an overall rating of 4.8 out of 5 stars from more than 200 users at Lowes.com and similar scores from owners at Amazon.com and on the manufacturer's website. Owners describe the 223L as powerful and easy to handle, with low vibration. Complaints about performance and reliability are rare. The only unusual gripe we saw was that hot exhaust is vented out the top, where it may burn the operator's arm. This seems to be a problem for left-handed users in particular. The Husqvarna 223L is backed by a two-year warranty.
A close second in the reviews is the less expensive Hitachi CG22EASSLP (*Est. $185) . Its 21.1 cc engine holds its own against pricier two-stroke competitors in tests at Popular Mechanics, and it gets mostly positive reviews at Amazon.com and Sears.com. The Hitachi CG22EASSLP has an anti-vibration system and a 60-inch straight shaft to extend the user's reach. It also meets California Air Resources Board (CARB) emissions standards, making it more eco-friendly than most other two-stroke gas trimmers.
Users praise this string trimmer for its easy starting and powerful, smooth operation. They are also impressed with the seven-year warranty, but several say they have had trouble actually getting service from Hitachi. The most common problem with this string trimmer is that the fuel lines have a tendency to crack and wear out, often after just one season of use. Owners say replacing them is fairly easy for a do-it-yourselfer, but getting Hitachi to do the repair can be a major hassle. A curved-shaft version of this gas string trimmer, the Hitachi CG22EABSLP (*Est. $155) is also available and scores well in comparison tests conducted by a respected consumer magazine.
The 21.2 cc Echo SRM-225 (*Est. $200) performs admirably in tests and gets good reviews (4.5 stars overall out of 5) from more than 140 owners posting at HomeDepot.com. This trimmer weighs 12 pounds and has a cutting width of 17 inches. Echo says it's the most fuel-efficient straight-shaft trimmer on the market, but unlike the Hitachi CG22EASSLP, it isn't CARB-compliant. In general, owners who submit reviews say the SRM-225 is powerful, sturdy and easy to start, and its bump-feed system works well. The five-year warranty is another plus, but as with the Hitachi, users warn that getting warranty service can be difficult. We also saw a few complaints that after a year or two, this trimmer becomes harder to start.
The Echo SRM-225i (*Est. $260) shares most of its features with the aforementioned SRM-225, but it includes a more sophisticated starting system. This model is the top performer in professional tests conducted by Popular Mechanics and ProToolReviews.com. User reviews are scarce, but more than 15 owners praise its power and easy starting in reviews posted at HomeDepot.com. That said, it's not clear from the reviews we read that this model has enough advantages over the basic SRM-225 to justify its higher price.
A less expensive gas trimmer that gets good overall ratings is the Craftsman 79120 (*Est. $160) . This straight-shaft trimmer has a 27 cc engine, a 14-inch cutting path and a two-year warranty. It's a solid performer in professional tests, with especially good results when tackling tall grass and weeds. This trimmer also gets mostly positive reviews from about 45 users at Sears.com, who say it's easy to use and is a good value. Owners' most common complaint is that this trimmer gets very hot during use, and several say they have burned themselves on the muffler. We also saw a few complaints that the engine is hard to start.
Four-stroke string trimmers, unlike two-stroke models, run on gasoline rather than a mix of gas and oil. We did not find nearly as many reviews for this type of gas trimmer; in one independent test, only three four-stroke models are included, and all of them fall toward the bottom of the rankings. However, one model, the Husqvarna 224L (*Est. $330) , gets high marks from about 100 users posting at Lowes.com. At 11.4 pounds, it's not very heavy for a four-stroke trimmer, and it has a 25 cc engine and a 58-inch straight shaft. Owners praise its general ease of use, low noise and vibration, and good handling. However, we did see some complaints about durability, and some owners say it's not worth its higher price. Like the two-stroke Husqvarna 223, this trimmer is backed by a two-year warranty.
For those who want the power and range of a gas string trimmer but don't want to bother with mixing gas and oil, a propane-powered trimmer can be a reasonable alternative. However, there are very few string trimmers on the market that take this type of fuel. Pretty much the only options are the curved-shaft Lehr Eco Trimmer ST025DC (*Est. $160) and its straight-shaft equivalent, the ST025DS (*Est. $180) . The straight-shaft model gets an enthusiastic thumbs-up from landscaper Allyn Paul at LifeAndLawns.com, who says the four-stroke engine is as powerful as a gas-powered trimmer's and "doesn't stink as bad."
The curved-shaft ST025DC, however, does not fare as well. The editors of GearPatrol.com recommend it, saying it's much easier to fuel up and start than a gas trimmer and every bit as powerful. However, in another professional test, its score is only middling: It does a very good job of trimming, edging and taking down weeds, but its handling is only so-so. Owners at Amazon.com seem to agree, complaining that this trimmer is heavy, unbalanced and hard to maneuver. David Beaulieu, About.com's guide to landscaping, sums it up by saying that the Eco Trimmer is a great model for lawn-care professionals, but for the average home user, its weight and "potential idling problems" are major drawbacks.