In the deep-powder world dominated by long tracks, narrow front ends, light chassis and motor displacements near 800cc, a small niche exists where the mountain-specific 800-class snowmobile covers hillclimb racing and backcounty freestyle riding. Such snowmobiles are Ski-Doo’s Freeride, Arctic Cat’s M8000 HCR and Polaris’ 800 RMK Assault, featured here.

Fast Facts

Engine Type:Horizontal In-line


Engine Stroke:2-Stroke

Valve Configuration:Reed Valve

Displacement:795 / 48.5



View Full Spec

Polaris’ highly popular RMK Pro 155 casts a shadow, albeit a small shadow, on Polaris’ 800 RMK Assault 155. Why is that? Well, the Pro RMK is uber light and has Polaris’ Quick Drive Low Inertia Belt Drive System – no chaincase. But, for heaven’s sake, the RMK Assault is crazy fun and ferocious on any hillclimb circuit. It is a mountain climber’s business office, suited for the toughest jobs.

As mentioned, Polaris builds the RMK Assault without the Quick Drive Low Inertia Drive System; reserving it for the RMK Pro. But, this does not make the RMK Assault a less-than “RMK.” The Assault retains the sturdy and trusted chaincase system. For the past two seasons as we grilled the RMK engineers about the lack-of Quick Drive, we were reminded the chaincase is demanded by professional hillclimbers who need chain and gears to handle turbo power and to be strong to take big rock impacts when the track drivers hit the granite objects, and to handle the stress when the track suddenly stops and in a nano-second, ramps up to full RPM as the driver keeps the throttle pinned to the bar.

COMPARISON: Read our review of the 2014 Polaris 800 Pro-RMK

Hence, Polaris designed the RMK Assault to be a defined RMK for hillclimb competitions. Yet, it is not for the racer only, it is designed for any deep mountain canyon explorer who likes to take a hit on the chin. The Assault with its large-volume Walker Evans piggyback shocks is configured to be a kid who can take it when slammed to ground zero from a 20-foot or more drop.

Like the RMK Pro, the Assault uses the Liberty Clean Fire 800 twin. The powerplant is Polaris’ Liberty 795cc two-stroke, liquid-cooled, Cleanfire fuel injected (CFI) Twin cylinder motor, which is rated at sea level with 150-plus horsepower. Bore and stroke is 85mm X 70mm. The motor comes complete with throttle position sensors, detonation sensors and PERC – Polaris Electronic Reverse Control. This motor is crisp and delivers stable power throughout its powerband. We’ve learned over the years the motor is reliable. And for the turbo geeks, its crankcase can take the pressure.

The standard track on the Assault is a 2.125-inch Competition block track, which has a stiff durometer. The stiff lugs allow the track to handle sharp rocks when traversing up a hill, and to dig into frozen dirt when encountered. The stiff block-pattern track muscles through hardpacked snow, however the track will cut a trench in feathery light powder. Also, the Competition track is short on lug height being only 2.125-incher. If driving the RMK Assault with the Competition track, understand that when descending the same hardpacked hill, the Assault can be a little untamed, as the track’s braking ability is not as sweet as the Pro’s track. There is good news though.

New for 2014, the RMK Assault can be ordered with the RMK Pro 155 Series 5.1 Mountain track that has 2.4-inch lugs. We find this sweetly appealing. Give Polaris an “Atta boy” here. When the RMK Assault came to be, I was confused as to why Polaris gave the customer the Series 5.1 Mountain track as a Spring buy option only. It did follow suit to the RMK Assault’s sistership, the Switchback Assault, which too is offered to a customer with two track choices, the 1.35-inch Camoplast Cobra, or the Series 4.0 two-inch paddle track as a Spring buy option. At, we felt the two track choices for the RMK Assault should be offered beyond the Spring buy option. Your and our wish is here, and we could not be happier. With that said, we imagine Rocky Mountain Polaris dealers ordered most 2014 RMK Assaults with the Series 5.1 powder track. Wouldn’t you?

Be in the know, the RMK Assault comes only as a 155, shorter or longer are out of the question – unless you choose to modify the Assault.

COMPARISON: Read our review of the 2014 Ski-Doo Freeride

Let’s sum this up by saying: for 2014, the RMK Assault has the same deep-powder finesse as Ski-Doo’s Freeride 154 and Arctic Cat’s M8000 HCR; customers who purchase the RMK Assault late (in the Fall) will not need to swap-out and dealer trade the Competition track for the Series 5.1 powder track. This may not mean much, but it is huge, as the RMK Assault now becomes an everyday-purchased two-dimensional mountain snowmobile that can dish out its best to its competitors.

The RMK Assault’s front and rear suspension is engineered to absorb, as we keep stating, big hits and big drops. Being the RMK Assault is designed to race, literally, up a hill, its front-end ski-stance is wider than the RMK Pro’s stance. The difference between the two is two inches, 43.5 and 41.5 respectively. Wider is better in that it helps the competitive driver throw down tight and crisp turns when chasing the timing lights up a much rutted course that weaves between gates.

With that said, the RMK Assault comes equipped with a competition-specific Pro Ride front end with compression adjustable Walker Evans piggyback shocks. Unlike other hillclimb race sleds, the Pro Ride front end does not use a swaybar, as the stiff valved Walker Evans shocks and wide front end keep the skis planted.  The front end has a vertical travel of 10 inches.

The rear skid is Polaris’ RMK coil-over with high-end Walker Evans Needle shocks. Vertical travel for the RMK coil over is 16 inches.

Like the RMK Pro, the 2014 RMK Assault comes equipped with PowderTrac running boards, the over-the-motor carbon fiber overstructure and Pro Lite seat, which we favor for its narrow and short profile. Though the RMK Assault has heavier shocks and a chaincase, its dry weight is 435 pounds – 18 pounds more than the 155 RMK Pro. The difference between the two is small. To that, the RMK Assault fits in nicely with its competitors’ lightest mountain snowmobiles.

Other standard features for the RMK Assault are Pro Taper handlebars and PERC, a lightweight brake rotor and Cyclone master cylinder. The Pro-Ride RMK has a vertical steering post with a series of 90-degree angles that deliver flat handlebar swing.

The RMK Assault’s multi function Gauge allows riders to choose either the tachometer or speedometer. Users can record hours and temperature, as well as trip distance and overall distance, and it has a built-in recorder that documents up to three minutes of run time; this information can be played back. For this new model year, operators can choose fuel type through the instrument pod; an ethanol jumper plug is not needed. There is a glitch, though, as we do not like the instrument pod’s angle. We lean toward rotating pods that can swivel upward to look up at the driver when standing, as most mountain riders do.

COMPARISON: Read our review of the 2014 Arctic Cat M8000 HCR 153

The RMK Assault is competition-made, that is true. But from our experience on the snow, be it whacking a mountain on a friend’s RMK Assault or assaulting one of Polaris’ units at a test session, we like the beefy muscular attitude the sled has. Though its ski-stance is two inches wider than the Pro-RMK, it compensates by delivering an assurance to its owner its front end can handle most abusive conditions. From the factory, its shock settings are stiff, but with the piggyback shocks, rebound and dampening can be dialed in to a rider’s need.

The RMK Assault has moved to deep-powder status as a standard tagline. What would we choose if given the choice to take home either the RMK Assault with Series 5.1 powder track or RMK Pro 155? That for us would be a crushing decision. Setting ourselves up with possible accusations of being politically correct and being indecisive, we truthfully state…. we do not know which we would choose. Yes, that sounds wishy-washy and safe, but both are sound choices.

2014 Polaris 800 RMK Assault 155 Specs
Engine Polaris Liberty, 795cc two-stroke, liquid-cooled, twin; Cleanfire electronic fuel injection; two-into-one exhaust
Horsepower 150+
Drive Polaris P-85 driver and TEAM LWT driven
Front Suspension Pro-Ride RMK adjustable A-arm suspension; Walker Evans gas shocks; 10.0-inches of travel; uses Polaris “Gripper” skis
Rear Suspension Polaris RMK coil-over parallel rail slide with Walker Evans shocks; up to 16.0-inches of travel
Length 129.0 in
Width 48.0 in
Width 51.0 in
Ski Stance Adjustable from 42.5-43.5-in
Track 15 x 155 x 2.15 Competition (Also: 15 x 155 x 2.4 Series 5.1)
Weight 435 (claimed)
Features Standard: Phantom hydraulic brake; ProTaper steering; Pro-lite seat; digital multi-function gauge, electronic reverse
Options: 12v-DC outlet, electric start, luggage, mirrors
Fuel Capacity 11.5 US Gal
MSRP $12,499