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Polaris’ new ACE 900 takes single-seat thrill to the next level

Posted in Features on January 2, 2016
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Photographers: Larry Walton

It was a short, steep climb. Narrow. Twisty. Rutted. Muddy. Just the fun little section of off-road trail that begs to be challenged. A stab of the throttle and a few seconds later I crested to top of the Tennessee backcountry ATV trail with mud slinging off all four wheels that were now grabbing at nothing but a couple feet of air.

The suspension sucked up the landing and a flick of the wheel kept everything under control as I dodged between trees and rocks as the trail continued up the mountain.

That’s the new Polaris ACE 900. It’s surprisingly fast, agile and capable—and true adrenaline-rush to drive.

Of course, what wouldn’t be when you slide a 60hp ProStar four-stroke in a 900-pound off-road go-cart, which is essentially what Polaris has with the newest offering in the expanding ACE line-up.

The ACE 570XP was fun to drive. But it lacked that kick when you nailed the throttle; it had to be run hard to feel sporty. Not so with the ACE 900. It has 15 more horses and a lot more torque than the 570, so now there’s probably more power on tap then anyone but a seasoned racer would be able to utilize to the fullest.

What’s different between the sporty ACE 570XP and the ACE 900 goes deeper than just shoehorning in the ProStar 900 (the original engine on the Ranger SP.)

“One of the first things our test riders agreed on was the [ACE] 900s need for a front sway bar,” says Jeff Lovold, ACE Systems Engineer, as we took a walk around the machine I’d been driving over the miles of trails in the Brimstone Recreation Area.

According to Lovold, the torque of the 900 engine would lift a front wheel off the ground any time you’d power out of a corner. Not a good thing on a short wheelbase, narrow machine unless you like racing midgets and modifieds.

So the Polaris’ engineering team added a solid steel front sway bar to keep both front wheels working in unison as the machine dives into a corner and powers out. They also redesigned the rear sway sway bar that was already on the ACEs, removing the slip-tube version and replacing it with a solid one to further stabilize the handling.

The front and rear spring rates have also been changes slightly to accommodate the heavier engine and front/rear weight ratio, which is now close to 50/50, which makes this machine fun to air out. Even though the new ACE is about 80 ponds heavier than the 570XP model, it lands with far less nose-down attitude than its less powerful sibling.

The new machine still rides a bit on the rough side. Fortunately the nice, deep bucket seats helps absorb some of the jostling of off-road driving, and the bolsters and automotive-style seat belt keeps you steady as you play with the power underfoot.

Getting all that power to the ground was also a challenge. They had to tighten up the front differential so now the automatic all-wheel-drive system locks up much faster than those in the smaller-horsepower ACEs.

“Once the high-performance front drive system in the 900 senses the slightest wheel slip in the rear, the ‘close-ratio’ differential locks the front axles to give maximum traction,” explains Lovold.

Another change: a RZR-style air intake. The “bed” of the ACE 900 is slightly taller in front to accommodate the air filter that now sits tucked up high behind the seats. The rear plastic is shorter at the rear to allow more air to flow out from under the back of the cargo area so the engine can cool better.

Then there’s the ACE 900s throttle, which is now drive-by-wire, giving a much smoother and quicker responding feel under foot.

Other than those changes, everything else remains the same as the other ACEs in the line. The 2016 ACE 900 is a really fun off-road machine to drive and would be a total blast in the open desert or dunes where the power and nimbleness could really be put to use.

A nice front/rear weight bias helps keep the Polaris ACE 900 SP on a more level plane when it catches air compared to the less powerful ACE models.

The 2016 ACE 900 SP in Stealth Black has an MSRP of $11,499.

The single-seat, sit-in design of the ACE places the driver in the center of the machne while the full ROPS cage provides added proetection. Intuitive automotive-style controls will be familiar to newer operators.

Independent A-arm rear suspension is the same as the older ACE models with 9.5 inches of travel. The rear sway bar in the 900 SP is now one-piece, and the rear coils are of a new dual-rate design to better accommodate the more powerful, heavier ProStar 900 engine.

The intake systems has been changed on the ProStar 900 so the filter sits high in the 900 SP’s bed, keeping it clear of potential water ingestion in situations like this.

Electronic power steering (EPS) on the SP and its short wheelbase make it easy to drive in more demanding conditions like slippery ATV trails lined with trees and other obstacles.

The air filter in the SP 900 sits high in the front of the plastic cargo box and is accessed by lifting up the snap-in plastic panel that’s part of the box floor.

The front differential is what Polaris engineers refer to as a “close-ratio, high-performance” version that locks the front driving wheels whenever the AWD system senses the slightest rear wheel slip.

Another addition on the new ACE 900 SP is a solid front sway bar to improve stability under power and hard braking. It’s mounted to special brackets welded to the frame.

The ACE 900 SP is fitted with a full-length skid plate and sports 10.5-inches ground clearance on its 48-inch track. This gives it an off-road advantage over longer, wider ATVs and side-by-sides.

Half-doors with reinforcing tubing and the roll cage are standard features on the 900 SP. Getting in and out of the machine from either side is easy.

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