2008 Polaris Outlaw 525 IRS ATV Test

January 30, 2008
By Billy Bartels
2008 Polaris Outlaw 525 IRS
Polaris came out with the IRS concept years ago and has found a terrific match with the new KTM-powered Outlaw platform.

Sitting atop a rise in the trail in Tennessee Mountain, Oregon (miles from anywhere) and surrounded by snow-covered rocks, we were struck with a thought: Polaris‘ Outlaw lives up to its name. This bad-ass machine breaks all of the rules of sport quads, will go just about anywhere, and truly looks the part with a unique, aggressive style.

Sport ATVing has a dirty little secret: Sport quads are less all-terrain than they should be. Focused more on the narrow confines of sand and motocross, most sport machines are not the best for when the terrain is truly challenging. Rutted, root-infested, muddy, rocky trails will all give the limited clearance of a sport quad fits as the low-slung brake and sprocket drag their way over the various obstacles that throw themselves in the way.

The culprit is the straight axle rear suspension. When cornering stability is key, it does its job like a champ settling the chassis and sliding around corners with confidence. However, in rougher terrain it creates some headaches with both a lack of ground clearance, non-independent wheel travel, as well as a ton of unsprung weight for the suspension to control when a bump is encountered by either rear tire.

When Polaris set out to create their second high-performance sport machine (after the ground-breaking Predator), they took some inspiration from what they had already learned in the sport market, but also looked to the strong suits of their utility machines. The front half of the new Outlaw is a lot like the ol’ Predator, utilizing a fairly standard setup of dual A-arms, but employing a linkage-style steering stem, designed to cut down on bump-steer. The back half is where it deviates significantly from the norm.

The Fox-Shox-equipped IRS works unbelievably well in cross-country style applications. Motocross and dunes are a different story.
The Fox-Shox-equipped IRS works unbelievably well in cross-country style applications. Motocross and dunes are a different story.

Independent Rear Suspension (IRS) systems, which were pioneered by Polaris, have been around for years. Until now they have mostly found their way onto large, heavy utility machines. While improving the ride of a “Ute” significantly at low to moderate speeds, once rolling at a faster pace the overall heft of the machine overwhelms the usually low-grade suspension components, and the quad tends to bounce off the stops.

However when IRS is applied to the relatively lightweight chassis of the Outlaw, it’s a whole different story. Peering under the back fenders, you’ll spot a rear-end unlike any other. The slightly rearward-swept A-arms with stout hi-tech Fox Shox look like they mean business. Somewhat like a conventional sport, the sprocket and rotor are centrally mounted. The difference is that they are located higher up on an extension of the rear half of the frame that also mounts the rear A-arms. While most utility 4x4s have a shaft drive (which is very well suited to life in an IRS rear-end), the Outlaw wears a chain, which has superior power transfer characteristics, gearing tunability and less weight.

The one basic drawback of this seemingly superior system is weight. While not toting around the heft of a rack-wearin’ Ute, the extra set of A-arms, shocks and a beefier subframe all add up to more weight than a high-end 450cc sport-quad.

Thankfully, it’s also toting around more ponies than a 450. KTM’s 525 (actually only a 510) is a cutting-edge single overhead cam, four-valve single cylinder engine. While overall power output is comparable to a typical 450 sport quad, it’s the bottom- and mid-range where the extra CCs really shine. Throttle response is immediate but predictable, and the Keihin FCR carb is so smooth and insensitive to different elevations and conditions that we had to check if this puppy was fuel injected.

One big difference from the motorcycle this engine is derived is the five-speed transmission with a reverse gear. Shifting is as slick as anything out there, and as always reverse is welcomed on any vehicle with four wheels and especially useful on the trails. The Magura hydraulic clutch is right off KTM’s bikes as well, and the extra pair of wheels has no effect on its excellent performance.

The KTM mill has six cogs  much like the 2-wheeled version it comes from  but one of those is a reverse in the Outlaw.
The KTM mill has six cogs, much like the 2-wheeled version it comes from, but one of those is a reverse in the Outlaw.

Quality components, which many riders immediately purchase aftermarket for their machines are also a hallmark of the Outlaw. The Fox Shox at all four corners are high-end units and give 10 inches of travel all round. Maxxis Razr-R radials are sought after skins for woods riders/racers and are mounted on decent spun aluminum rims. The brakes are solid units, with the addition of braided steel-reinforced lines helping to give a solid feel and feedback at the lever, and less fade when worked hard.

However, there are some questionable build qualities, perhaps harkening back to Polaris’ focus of building tough, low-impact utility quads. It’s little things that are bound to drive a real abuser (racer) mad, like tapped holes in the frame to mount bodywork instead of a welded nut or steel thread insert. The fasteners in general are all over the map needing a variety of tools including metric, SAE and Torx bits to do some of the simple maintenance. Two things that need help from the aftermarket right away are the skinny steel handlebars and the flimsy heel guards.

So, being the first sport-quad made for extreme terrain, we took it to some. Luckily, here in Oregon we’ve got some of the gnarliest rocky woods anywhere, which led to that moment of truth up on Tennessee Mountain. It’s simply at home in the rough stuff. With slippery rock surfaces, deeps ruts, patches of snow, and roots everywhere, it was like a mountain goat. A really fast mountain goat. The IRS suspension is so far ahead of fixed axle quads that it’s simply mind boggling. Leading the way is the 11 inches of ground clearance under the length of the machine. When you hit something with the undercarriage, you see it coming! The IRS enables the rider to keep maximum control by keeping all four wheels planted on the ground most of the time, delivering traction on demand and clearing obstacles like magic.

The suspension system also contributes to overall comfort. The effort required to ride the machine in challenging terrain is virtually nothing, as your body gets pounded less by the bumps and ruts. It extends the time you can ride without a break, and leaves you fresher for longer. Comfort-wise its similar to an IRS-equipped sport-utility ATV, but you can push far harder on the Outlaw, and you never miss the lack of front-wheel drive.

Higher ground clearance and independent rear suspension make sliding the Outlaw more difficult than standard 450 sport-quads.
Higher ground clearance and independent rear suspension make sliding the Outlaw more difficult than standard 450 sport-quads.

The downside of the IRS in a technical woods setting is in sidehill situations. A typical straight-axle machine might slide its rear wheels downhill a bit when off-camber, but the Outlaw tends to just lean that way and steer downhill which is even more difficult to handle. It takes a bit of finesse (and a lot of weight shift) to keep it pointed the right direction. 

In the drier, faster mountain trails of Southern California the Outlaw is actually almost as comfortable as in the tighter woods. In places with less rainfall the more-used trails tend to get pocked and pitted, along with healthy doses of rain ruts going every which way. In short, the rougher the better, and, funny enough, the Outlaw isn’t as good when conditions are smoother. On flatter/smoother terrain, or in the sand, the IRS is counterproductive and digs-in rather than sliding predictably, meaning you might have to ease your pace or adjust riding styles to compensate. Also, when performing big jumps or hitting “g-outs” the fenders can rub hard on the tires and create a disagreeable noise, to say the least.

“The first time I heard the fenders rub I thought the entire thing was coming apart underneath me,” says MotoUSA’s Editorial Director, Ken Hutchison.

In the higher-revving reaches of high speed riding, the torquey mill enjoys less of an advantage versus lesser-displaced quads, but between the greater comfort in the rough stuff, and less shifting to get in the power, it’s less work to ride overall.

Jumping can result in some disagreeable noises from the fenders rubbing against the tires. Small stuff like this is acceptable  but larger impacts will have the Polaris crying out in defiance.
Jumping can result in some disagreeable noises from the fenders rubbing against the tires. Small stuff like this is acceptable, but larger impacts will have the Polaris crying out in defiance.

One caveat to the Outlaw’s “rougher is better” attitude is in big whoops. While its no slouch and can gobble up smaller rockers, its 425 tank-empty pounds can be a drawback when really pounding the big ones, at least compared to other true high-performance machines.

The only things it isn’t particularly suited for are straight motocross track riding and sand dunes. A competent rider will have a good time on either one if the need arises, but the extra weight and complexity of the rear suspension is not a welcome addition in either environment. The simpler straight axle of other quads is perfectly suited to either one, as is confers a confidence cornering that the IRS-equipped Outlaw does not. The 525 will slide, but it likes subtle bar input and requires a good feel for what the machine is doing.

On the other hand if cross-country racing is your thing, the same virtues that make it such a good challenging-terrain trail quad, make it an easy machine to hop on and race in similar conditions. The deeps ruts of a XC course and generally “worked” conditions also play right into the Outlaws’ strengths. In fact, places where many enthusiasts might think would call for a 4×4-style machine, are like home to the Polaris, with light weight and maneuverability making up for powered front wheels. The only drawbacks in tight “between the trees” conditions are the wide sport quad stance (47.5″), which tends to reach out and tag roadside attractions when you might least expect it. Desert racing is also a strong point for the Outlaw, at least for sportsman-class riders. The suspension quality shows some limitations in balls-out riding, but the nearly four gallons of fuel in the tank makes for additional range. The unique chassis sometimes reacts in interesting ways when taking big hits, and not always like you’d expect. The bump-steer-limiting front end setup seems to work better at lower speeds as well.

You only need to look around at the field of high-end sport quads to see that the Outlaw is a unique-looking ATV. Missing the ubiquitous scalloped stripes of just about every other machine, and wearing a front visage that resembles a skull, the old west-inspired graphics really stand to set it apart. They also do a good job of looking fresh, holding up well to a couple months of abuse very well. The only part that failed our (repeated) rollover testing was the handlebar clamp cover that also holds the ignition switch. That said, at least the bars were still straight.

There s plenty about the Polaris that s big. The seating arrangement is spacious and the larger motor has an advantage over 450cc machines.
There’s plenty about the Polaris that’s big. The seating arrangement is spacious and the larger motor has an advantage over 450cc machines.

Sport ATVs are in a defining moment in their history, splitting between light, race-ready machines in the 450cc category, and larger-displacement, torquey and comfortable machines sitting at 650cc on up to around 800. Splitting the difference (and breaking the rules) is Polaris’ true Outlaw. With just a bit more weight than the 450s and a similar-sized chassis, it may not compete in the ultra high-performance realms of sand and moto, but it doesn’t fail either. When looked at next to the almost-utility quad-sized monsters in the 700-and up category, it brings many of the same refinements (and even some of the power), without a massive weight penalty. The real revelation is the fully-independent rear suspension system, freeing the Outlaw from the straight-axle shackles of most sport ATVs, and making it far more worthy of the moniker “All Terrain Vehicle” than it otherwise would be. It’s no longer unique in this regard, with a Honda and a Can Am sporting independent suspension, but it is way cheaper and lighter than either of those machines.

With the larger machines mostly going to “old guys” a step away from riding a 4×4, the Outlaw stakes its rutted, pitted, sloppy ground as a perfect machine for the aggressive rider who rides where the ground is just as aggressive and challenging. At $7399 its in the ballpark with all of the 450s, ties with Yamaha’s Raptor, and is hundreds less than other IRS-equipped sports. For its not-so-specialized niche, that’s a good place to be.

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