We vividly remember throwing a leg over the REV-XP-based Ski-Doo MX Z X 800R snowmobiles in the spring of 2007 when they were introduced to the snowmobile media for model year 2008. During those first rides we were impressed by the way the lightweight chassis’ optimized ergonomics enabled riders to take advantage of the gutsy 800R engine and make the sled lunge through berms, carve around corners and launch off of moguls like a dirt bike. That light and powerful Ski-Doo was a riot to ride, and its chassis set a new benchmark for rider influence and control.

Fast forward nine years to the spring of 2016 and we were at it again: comparing performance attributes of the next generation Ski-Doo MX Z X to that of two-wheeled dirt scooters – exhilarating machines that are often considered the ultimate off-road weapon thanks to their impressive power-to-weight ratio and uncanny ability to conquer troublesome terrain.

But the 2017 Ski-Doo MX Z X 850 E-TEC is just that – an exceptionally fun, maneuverable and capable sled built for rugged trails and aggressive riders. The new 850cc engine is remarkably responsive, and thanks to an all-new chassis and steering system, the frame that surrounds all of that power rails through corners.

2017 Ski-Doo MX Z X 850 REV Gen4
The 2017 Ski-Doo MX Z X 850 is built on the new REV Gen4 chassis that’s more stable and predictable through bumps than the REV-X chassis it replaces.

New features found throughout the 2017 Ski-Doo MX Z X 850 E-TEC include the pDrive clutch, second generation E-TEC fuel system, rack steering, a uniquely adjustable handlebar, revised ergonomics, sleek-yet-simple styling, advanced pistons, a two-piece crankshaft and more.

Saddling up on the MX Z built on the new REV Gen4 chassis feels familiar but different. The distance and relationship between the handlebar, seat and foot wells is similar to other Ski-Doos, but the narrower seat is about an inch taller than REV-XS machines, according to our measurements, giving a surprisingly improved view of the trail and a more upright posture. It feels more aggressive. Fortunately, the seat is soft and comfortable. Also contributing to the better view of the trail, the bulkhead has about an extra inch of ground clearance compared to the REV-XS chassis.

By pulling on a spring-loaded ‘T’ handle between the driver and steering post, riders can choose one of four handlebar positions. Once he or she finds the preferred setting and releases the handle, a metal pin snaps into a slot and solidly holds the bar in place without any rattles or looseness from the system. One click down from the forward setting was the spot preferred by most Snow Goer magazine test riders.

The beveled tunnel allows the knees and legs to feel natural and relaxed, but the chaincase and brake cover protrude into the foot wells like earlier Ski-Doo REV models, which makes the sled feel wide down low and when standing with feet in the wells. The open foot wells seem strange at first and make feet feel unrestricted so a rider can easily move around the cab.

2017 Ski-Doo MX Z X 850 E-TEC Advanced Ergonomics

Ski-Doo REV-XP models feature a notch in the bottom of the side panels so drivers can tuck their shin in the cutout and lean farther out through turns. The REV Gen4’s Ergo-Step side panels take that concept a step further.

When running fast into whooped-out corners on the new MX Z X, we could square up the machine at the apex by rapping the throttle while simultaneously nudging the handlebar (to turn the skis) and pulling on the outboard end of the bar to lighten the outside ski – seemingly pulling the sled onto its inside side panel. The taller ride height makes the MX Z X 850 E-TEC feel bigger, but it certainly doesn’t drive big.

All of these coinciding actions were enabled by the ultra-responsive engine working in concert with advanced ergonomics that encourage the driver to use his or her body in ways that weren’t possible on a stock snowmobile – until now.

The unique console set-up felt totally natural and Snow Goer test riders learned right away how to effectively use it. In fact, there were times while riding when we’d forget the Ergo-Step feature was there because it works without inhibiting movement or requiring drivers to think about how to take advantage of the console. It promotes flat, smooth-trail cornering and sharp handling by allowing active drivers to move forward and outward to help keep the inside ski on the snow. This also lets drivers get back on the gas sooner and with more vigor after rounding the apex of a turn.

What’s also impressive is that Ski-Doo engineers created the Ergo-Step feature to work in harmony with the handlebar and steering post so the bar doesn’t end up awkwardly out of the driver’s natural range of motion or up near the neck or face. For riders who aren’t interested in taking advantage of the new console by moving their bodies so much, the sled handles well without the driver sliding into the Ergo-Step area.

When hammering through moguls and trail chatter, the RAS 3 front suspension and new steering system makes the chassis feel tighter and there’s much less jarring and impact felt from the bumps than the RAS 2 and prior Ski-Doo front suspensions. The machine is easier to control and suffers from significantly less bump steer thanks to the rack steering set-up, which causes less movement at each end of the handlebar for a ride that’s less tiring and more enjoyable. However, X models with the rack system have a wider turning radius than TNT models with a pitman arm set-up, which benefits from the Ackerman steering effect by letting the inside ski turn farther inside than the outside ski. So, a TNT turns tighter but we prefer the reduced bump steer of the X package.

2017 Ski-Doo MX Z X 850 E-TEC Engine

Not to be outdone by the unique ergonomics, the new Rotax engine also helps to make snowmobiling more fun.

The 850 E-TEC powerplant in the pre-production sleds we drove at our Montana-based Rode Reports test event in February and back home in Minnesota a few weeks later flat-out ripped. Its fiery and fun power curve made it hard to resist cracking the throttle every chance we got, even if it was only to shoot forward just a short distance between corners. That rewarding response seems to encourage hooliganism.

Compared to the robust 800R E-TEC engine, the new 850 E-TEC is more lively, it spools up quicker and feels like it’s more willing to free-wheel
– making the sled it’s attached to feel light and free. Its performance attributes are similar to that of Polaris Cleanfire engines, oil burners we’ve admired for being responsive and fun. Push the throttle to accelerate out of a corner on the new MX Z X and, if the driver doesn’t also squeeze the handlebar to gain a little more grip, it forces him or her back in the saddle.


Credit for the impressive response is at least partially due to the second-generation E-TEC fuel system’s set of boost injectors in the intake tract, which gives the engine more fuel when the driver stabs the throttle. Their location is directly before the cylinder’s intake port, so that short path lets the gasoline go to work right away. The new drive clutch also helps the powertrain feel more reactive.

On the other side of the cylinder, the Rotax 850’s exhaust system has a more-menacing sound than that of the 800R E-TEC, emitting a note that could be described as a snarl or growl when the driver opens the throttle. Fortunately the sound is pleasant to the ears so drivers probably won’t ever grow tired of hearing it sing its sweet, powerful song.

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