From the May/June 2012 issue of ATV Rider Magazine.
Finally, I’m allowed to open my mouth again; which if you’ve ever met me, you’ll know that I’m not the type to hold my tongue. I enjoy the sound of my own voice, and I’m not afraid to tell you how I feel. My mom tried to simmer me down, but she knows I learned it from her. Back to point, when Polaris introduced the Ranger RZR 4 XP 900 in early 2011, I caught wind of the development of a four-seater version. I was overwhelmed with excitement, and you wouldn’t believe how stressful it was to keep it a secret. At the time, I had already acclaimed the original RZR 4 to be the best-handling UTV I’ve ever tested. I’d even pick the RZR 4 over the two-seater RZR XP because of its EPS option and the ability to tote all three of my friends. Today, I’m a happier man. The Polaris RZR XP 4 900 UTV is available to the public, and it’s everything I thought it would be. In the words of Brooks & Dunn: “Boot scootin’ boogie!”`
Suspension, Suspension And Suspension
It’s amazing how far Polaris has taken the RZR lineup in such a short amount of time (2008 to 2012). The RZR XP 4 900’s chassis is super sick and provides the most comfortable, stable and best handling characteristics on the market. Yes, that includes the two-seater RZR XP and Arctic Cat’s all-new WildCat 1000i. If you don’t believe us, stay tuned for the High-Performance UTV Shootout later this year. The RZR XP 4’s 107-inch wheelbase not only gives it the space for an extra two seats, it helps keep the extreme performer in control at all times. It’s a challenge to get this thing off track.
Up front is a double A-arm setup that offers almost 2 inches more wheel travel (13.5 inches) than the original RZR 4. Walker Evans race-inspired premium shocks have preload and compression adjustments, so the driver can fine-tune the ride. The rear end features a three-link trailing arm independent rear suspension. The three-link design consists of two radius rods and a far forward-connecting trailing arm. The trailing arms connect forward in the chassis to provide 14 inches of rear travel. Radius rods extend deep into the wheel hubs and feature geometry that optimizes camber. Tires lean into the corner through the suspension travel and plant more tire surface on the ground for a ridiculous amount of control. While the front Walker Evans shocks have 2.0-inch shock bodies, the rear utilizes a set of 2.5-inch diameter shocks. This was to compensate for the two extra passengers and overall weight of 1,390 pounds. The larger-diameter shocks stay cooler longer as well as offering more damping control.
The Polaris RZR XP 4 offers large amounts of wheel travel (13.5 inches in the front, 14 in the rear). At normal ride height the XP’s wheels can come up 11 to 12 inches without bottoming out or scraping. There is also 1 to 2 inches of sag in the ride height, which allows the wheels to fall into holes using up the other couple of inches of wheel travel. We were skipping over 3- to 4-foot whoops comfortably for miles. Square edges and G-outs were no match for the 14 inches of wheel travel, and 12.5 inches of ground clearance allowed us to fly right over large rocks.
The XP rides on cast-aluminum wheels with 27-inch Maxxis Bighorn tires. Dual hydraulic discs with dual-bore front and rear calipers bring the beefy six-ply treads to a halt in both the front and the rear. These are the best working brakes in the UTV market, bar none.
Polaris’ UTV-Exclusive ProStar 900 EFI Twin
The RZR XP 4 900 utilizes the same ProStar 900 EFI twin found in Polaris’ two-seater version. It’s the first motor specifically designed for a UTV by any manufacturer. Yamaha’s Rhino, Kawasaki’s Teryx, Arctic Cat’s Prowler and each of the previous pre-XP RZR powerplants are all based off their ATV counterparts. The 875cc ProStar is a dual-over-head-cam engine and uses four valves per cylinder. It runs parallel with the chassis and uses a 180-degree crankshaft to bring an acclaimed 88 horsepower to the rear wheels. The RZR 800 mill is mounted perpendicular to the chassis, and the power is run through a series of 90-degree angles. Aside from having a 125cc larger powerplant than the RZR 800, the ProStar has a much snappier throttle response, accelerates quicker, runs smoother and quieter and requires less maintenance.
An electronic fuel injection system is the heart of the RZR XP 4, and it pumps high-octane blood via dual throttle bodies that have worked flawlessly in the Ranger RZR lineup since 2008. It makes no difference whether you’re in freezing cold temperatures, are in high-altitude mountain ranges, surfing dunes or slamming down the coastal trails of Baja, California, the RZR XP 4 will always fire with the turn of the key, and that impressive DOHC sound will widen your eyes, tingle your toes and grow hair on your chest.
Since the birth of the RZR XP 900 in early 2011 a slew of aftermarket motor builders have popped out of the woodwork and into the advertising pages of ATV Rider. Does the ProStar 900 really need these upgrades? Depends on the consumer, but the average weekend warrior will not need more power from a UTV. The RZR XP 4 will hit speeds approaching the 70-mph mark with four passengers, and the motor is backed by a factory Polaris warranty. Aftermarket motor mods will negate your warranty. However, there are many people (you know who you are, Eli…) who will want to take that premium suspension package to its limits. This motor has the potential to hit triple-digit speeds.
Fuel mileage is not as efficient as the smaller cc RZR models, but the 7.5-gallon fuel tank still offers over 75 miles on a tank. That’s a bit more range than the heavy-duty truck it will need to tow the RZR XP 4. If you decide to make motor mods, an aftermarket fuel tank will be needed for extended time on the trails or dunes. Air is filtered via a large, rectangular K&N-style air filter located in the rear bed compartment. This Polaris unique airbox system incorporates dual vents on each side of the bed that funnel into the box’s secured filter located under the small bed compartment. Each vent has its own foam filter that is easily removed for cleaning. After six hours in the heavy dust, the side vents had slight dust, but the main interior filter had only small specs of dust. The bed compartment also has a lid for quick access to check the oil, plugs and electrical. The XP was designed for the owner to keep it easily maintained.