Can't decide between two-cycle and four-cycle technology when it comes to a string trimmer? Don't bother: The Stihl FS09R gas-powered trimmer combines the benefits of two-stroke (also called two-cycle) and four-stroke engines into an impressive new hybridization that's both clean-running and power-efficient.

Yes, this trimmer's 28.4cc engine is on the lower end of Stihl's professional offerings, but it does offer more juice than the company's occasional-use models -- at a higher price tag. If you're in the market for a trimmer that you'll only use for small or sporadic tasks, you'll want to consider a less expensive model.

What's especially intriguing about this unit is what the manufacturer has dubbed 4-MIX technology. The FS90R's 4-MIX engine uses the oil-and-gas mixture of a two-stroke engine, which lubricates all the mechanism's moving parts, no matter at what angle it's held. That's a particularly important feature for a string trimmer, which often needs to be tilted, turned or twisted to find just the right cutting angle. The design also incorporates a two-stroke engine's efficient power and light weight -- the whole trimmer weighs just 11.7 pounds -- with fewer moving parts than most four-stroke engines. But it also borrows the best features of a four-stroke, including up-to-snuff EPA and CARB emissions compliance, less noise and vibration and a much more reliable, low-maintenance design.

The Stihl FS90R offers an additional measure of flexibility. Its mix-and-match design lets you replace the standard two-line auto-cut trimmer head with a wide variety of optional accessories, such as a mini-cultivator, bristle brush or pole pruner. If you're worried that the FS90R's string-trimmer skeleton isn't up to accommodating a heavy-duty accessory, don't be. The solid drive shaft provides plenty of durability for even the toughest add-ons.

With its 4-MIX engine and professional-level design, the Stihl FS90R definitely deserves consideration, especially if you're torn between two- or four-cycle technology.


Pros: Hybrid 4-MIX engine combines the best qualities of two- and four-cycle technology
Cons: Price matches its professional-level features

Warranty
1 year, commercial use; 2 years, residential use