Polaris 800 Pro-RMK 155: The King’s Throne to Lose

A number like 417 is incredibly powerful for the mountain class. Polaris used this number to virally state an all-out attack on girth, and the competition. As the estimated dry weight of the 2013 800 Pro-RMK 155, 417 pounds is 42 pounds lighter than the Ski-Doo’s claimed dry weight of its 154-inch Summit X. That’s a tremendous advantage in performance where pounds are unwanted and maneuverability is top priority.

Polaris incorporated big-time changes to the new RMK to get the weight down and, more so, to reduce rider effort in maneuvering this machine. Different than Ski-Doo, Polaris engineers focused on reducing weight and, more importantly, rotating mass, which is the worst kind of weight because it takes more effort to move weight with centrifugal forces than it does stationary weight.

Polaris engineers accomplished this with the QuickDrive low inertia belt drive. According to the Polaris team, QuickDrive offers a 21 percent reduction in rotational inertia and, if we quickly run the numbers here, that’s about 5 pounds less effort to get this machine to lean over. They also say the QuickDrive system weighs 6.5 pounds less than the chain-driven system.

The new carbon fiber overstructure — tube above exhaust pipe — reduces weight.
The new carbon fiber overstructure — tube above exhaust pipe — reduces weight.

Next up in the cooler-than-crap category is carbon fiber. Polaris is selfishly using this inside the chassis where you can barely see it supporting the steering structure. Why carbon fiber? Because it’s lighter and strong.

Going with the bond-theme that Polaris debuted on its Rush trail sled in 2010, Polaris has glued together more parts of the RMK. Adding to the glued list are the A-arm tubes, shaving about a pound. Another pound comes out of the new, minimalist seat that’s shorter and easier to clear when climbing around the sled.

Are you going to notice all of these things right away on a new RMK? Not really. It’s always nice to lose a couple pounds, but of all the headlining changes Polaris HQ pumped out before we got to ride the new RMK, the seemingly simplest of them was the most in-your-face and noticeable.

No matter how hard we tried, we couldn’t get the PowderTrac running boards to hold snow.
No matter how hard we tried, we couldn’t get the PowderTrac running boards to hold snow.

We’re talking running boards. You’re probably thinking, “Polaris puts a belt where a chain was, adds carbon fiber and glues A-arms together and Snow Goer wants to talk about the things I stand on? Why?” That’s easy — the running boards were the RMK’s biggest weak spot for the past two years. Backcountry reports of bending boards were rampant and those in the know would replace or, at the very least, reinforce the stompers on the first- and second-generation RMK sleds. Polaris solved a pain point in its design and, oh yeah, the new PowderTrac running boards are insanely good.

Massive snow evacuation holes, beautifully carved traction cleats and a promise of “they won’t bend” from the Polaris officials were enough to sell our crew before our rides. After our rides, everyone commented on how good they were. PowderTrac running boards simply gave excellent traction and refused to allow snow buildup.

The Pro-RMK is as solid feeling, predictable and robust riding as last year. But now it’s a lot better because everything you loved to do on the 2012 is even easier to do on the 2013. With less weight spinning on the end of the jackshaft and driveshaft, there is less centrifugal force planting the sled on the ground when you want to lift a ski and there’s less inherent momentum carrying the machine forward when you want to slice an ‘S’ curve in the snow.

A-arm tubes are bonded to help bring the Pro-RMK’s weight down to 417 pounds.
A-arm tubes are bonded to help bring the Pro-RMK’s weight down to 417 pounds.

A lot of the challenge about riding in the mountains is getting past one’s own head and having the confidence to execute a tight powder turn before a tree well would swallow the sled, for example. When test riding the 2013 Pro-RMK, we felt more confidence than ever in our own abilities to make the machine do what we wanted and needed it to do. It is incredibly effortless to tip up and hold on one ski.

Testers who rode the 2013 Summit X before jumping on the 2013 Pro-RMK thought Polaris’ spot on top was in trouble. Ski-Doo came to the fight this year with a greatly improved mountain machine that might have knocked last year’s Pro-RMK out of first place, but since Polaris also has new iron that raised the bar for powder performance, the Pro-RMK is still the most maneuverable and easiest sled on the snow for taking on the biggest mountain terrain. Period.

The drivetrain improvements are great, yes. They work. But even though they aren’t as noticeable as the PowderTrac boards, the great pull of Polaris 800cc engine, the fantastic ergonomics and the benefit of less rotating mass and exotic materials, the Polaris still feels like it did last year — quite a bit better than everything else.

Polaris 800 Pro-RMK 155  / $12,199
CLAIMED DRY WEIGHT: 417 pounds ENGINE: 795cc liquid-cooled twin, Cleanfire Injection, bore/stroke 85×70 mm TRACK: 15x155x2.4 Series 5.1

See how the Polaris 800 Pro-RMK fared against other sleds in it’s class at the 800-Class Shootout!

2 thoughts on “Polaris 800 Pro-RMK 155: The King’s Throne to Lose

  • My dad picked up the 2013 Polaris RMK PRO 163. I have not done any serious riding previous to the purchase, so i virtually had no experience snowmobiling. All i can say is this sled is miraculous. Either i am a natural and picked up riding techniques very quickly or it takes the most inexperienced rider and make him look like he may actually know what he’s doing! And I believe that it’s the sled’s doing!!


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