New 800cc+ Mountain Sleds

The 2017 crop of hillclimbers includes the Ski-Doo Summit X 165, Polaris 800 AXYS Pro-RMK 174, Arctic Cat M 8000 Mountain Cat and Yamaha Sidewinder M-TX
2017 Ski-Doo Summit X 165 snowmobile
Ski-Doo's new REV Gen4 gets a facelift and some liposuction for a bold new look that its ancestors would be proud of, as well as an engine that will redefine 2-strokes.
Ryan Thompson - RLT Photos
Big changes usually mean big bragging rights.

This year, the 2017 battalion of 800+cc mountain sleds boasts just that – some huge changes! There’s a fleet of new sleds to choose from that is nothing but awesome.

Ski-Doo and Yamaha own bragging rights for the most significant changes this year: Ski-Doo engineering a top-to-bottom overhaul of the REV platform with its Summit X 165, and Yamaha showcasing the 998cc turbo Sidewinder M-TX. However, Arctic Cat and Polaris will also satisfy your craving for advancements with AC’s new M 8000 Mountain Cat with improved sidehilling and Polaris’ introduction of the 800 AXYS Pro-RMK 174. 
2017 Ski-Doo Summit X 165 snowmobile
2017 Ski-Doo Summit X 165
Ryan Thompson - RLT Photos
Ski-Doo Summit X 165: Not Your Daddy’s Sled
The first thing consumers will notice about the Ski-Doo reboot is the look of the new Gen4 REV and its throwback to sleds of the past. While the look is getting mixed reviews, I personally like the nod to the classics. Like a one-hit wonder, it tends to grow on you.

Ski-Doo’s revamped REV platform positions the rider even more forward and centered, which is designed to give improved steering response, handling and ride. The more rider-forward position was created, in part, to keep the snowmobile rooted on sidehills, but AmSnow test rider Lonnie Thompson believes it can have a different effect in some conditions. “It can cause a ‘pressure point’ or ‘anchor spot’ in some sidehill situations, causing it to wash out,” said Lonnie. That aside, one thing we all agreed on is the new Summit X responds to rider input with very little effort.

With today’s aggressive backcounty style of riding, don’t expect a beefy seat on any mountain sleds; this sled is designed to make standing and maneuvering more comfortable. One small yet appreciated change is the flattened out panels in the knee and shin area that make keeping your legs together much easier. Holding a line on a steep sidehill is easier than ever with the narrower platform, as well as the vertical spine running boards that sift through the deep snow without drag and buildup. The flatter foot position is subtle but noticeable and feels more balanced. The jury is still out on the open foot stirrup, with some heralding the change and others wishing they would have left it enclosed.

The Summit X’s completely new 850cc E-TEC engine is compact and centered with a two-piece forged crankshaft and plasma cylinder coating. In addition, it has directly oiled crankshaft bearings and boasts an additional 10hp for a total of 170hp (per Dynotech Research). So, there is more power similar oil economy to the 800R. The 100% new pDrive clutch is smaller and lighter than the TRA VII, and engineered to last longer and give the Gen4 REV platform quicker response. Even the track is improved; Ski-Doo added more space between the lugs to give the sled a more solid footprint by packing in more snow. All of these changes also translate into a sled that is 25 lbs. lighter.

With all of these upgrades, the AmSnow mountain test riding posse is very impressed with the engineering put into the Ski-Doo Gen4. It’s easy to handle in all snow conditions, and everyone agrees that most of the details were thoroughly vetted before making the cut.
2017 Polaris 800 AXYS Pro-RMK 174 snowmobile
We are waiting for a 4-foot powder dump, because Polaris hit a home run with the new 800 AXYS Pro-RMK and its 174-inch track. It’s a force to be reckoned with!
Ryan Thompson - RLT Photos
2017 Polaris 800 AXYS Pro-RMK 174 snowmobile
2017 Polaris 800 AXYS Pro-RMK 174
Ryan Thompson - RLT Photos
Polaris 800 AXYS Pro-RMK 174: No Diving Allowed
Polaris introduced the AXYS chassis to the mountain lineup in 2016, and it continues for 2017. The big news this year for Polaris is the much anticipated 800 AXYS Pro-RMK 174. Polaris moved the skid’s rear swing arm back, decreasing the tendency to trench while also keeping the snowmobile relatively flat. Bottom line: This sled floats even more.

We were very impressed with how much power the 165-hp 800 H.O. engine had in the 174 length. Even with the longer track, the engine did not feel like it was lacking in response or power. In fact, in a quick side-by-side comparo with the Ski-Doo 174, the AXYS came out of the hole faster, leveled out, and stayed in an easy-to-maintain line better than its Ski-Doo counterpart. However, the Ski-Doo caught and passed the Polaris about a quarter of the way up, but the AXYS didn’t sway side-to-side or push as much snow as the Summit X 174.

Polaris touts its new RMK 174 for its instantaneous lift and ability to avoid getting stuck. This type of statement is always one that we try to prove wrong, but so far the Polaris has come out on top (literally) as the 174 track and raised chassis keep the skis from diving and the sled from trenching. This translated into less digging time for the rider and less overall ibuprofen consumption.

The AXYS 174 has a 39-inch front end, but you really don’t notice the width when sidehilling or carving a meadow, highlighting how well the geometry of this sled works. Still, one test rider thought it pushed through the corners a bit when compared to Ski-Doo and Arctic Cat.

We were also glad to see Polaris beefed up the front bumper and got rid of the carbon fiber back bumper. We hoped to see a change to the A-arms, as many thought Polaris sacrificed strength for weight with the introduction of the new A-arms in 2016, which remain on the 2017 model.

The PIDD (Polaris Interactive Digital Display) is, in our opinion, the best display on the market. A feature that was only available as an upgrade now comes standard on the Pro-RMK lineup. Bright and sharp with several different display options (including night and day), the PIDD also includes Bluetooth and GPS.  Additionally, Polaris offers a smartphone app that connects to the PIDD display via Bluetooth. Also standard on the 174 LE are the small Burandt tunnel bag, underseat bag and handlebar bag for storage.

Polaris is an industry leader in the mountain segment for a reason, and the 800 AXYS Pro-RMK doesn’t disappoint.
2017 Arctic Cat M 8000 Mountain Cat snowmobile
The new Mountain Cat is incredibly aggressive and fun to ride. It’s an impressive sled with a lot of subtle changes to make a big difference.
Ryan Thompson - RLT Photos
2017 Arctic Cat M 8000 Mountain Cat snowmobile
ArCtic cat’s narrower running boards help to improve the traction on steeper side hills.
Ryan Thompson - RLT Photos
Arctic Cat M 8000 Mountain Cat: You Will Need a Chain for a Leash
Arctic Cat offers an aggressive package with the 160-hp M 8000 Mountain Cat. Although not the complete overhaul we anticipated, this sled is still a top-notch ride, and lighter for 2017. Many expected to see a new 800 C-TEC2 motor this year. While this is not the case, rumor has it that it’s on the way for 2018.

AC made relatively few changes compared with the other manufacturers. However, some of the changes will have a major positive impact on the way you ride.  
The biggest change was lowering the driveshaft 1.125 inches, providing increased clearance for the 3-inch track lugs. The drive sprocket is now an 8-tooth drive instead of 7, creating a flatter approach angle to the snow. This gives it better handling and flotation on deep powder days and, similar to the AXYS platform, allows it to climb up on top of the snow quicker.

The 1-inch-narrower running boards and the 2-inch-forward placement of the stirrups from the previous year helps the rider maneuver steep sidehills. Our test riders thought this sled felt light and nimble in technical situations (i.e., a steep slope with trees), and it was on top of the snow the instant the throttle was cracked. This sled holds a sidehill well, is easy to maneuver, and doesn’t dive as badly as the last couple years of M-sleds.

One of the things Cat seems to be happy about is the new low-profile hand grips, which are 3.7mm smaller in diameter. This is supposed to have a significant impact on comfort and ergonomics. While we didn’t really notice a difference while riding, most ergonomic improvements are best evaluated over a full season.

Although there were not as many changes to the sled when compared to other OEMs, our lack of discussion points shouldn’t be deceiving. You don’t always need to change a good thing.
2017 Yamaha Sidewinder M-TX snowmobile
Yamaha engineers (along with Arctic Cat) created a sled that generates mind-numbing speed!
Ryan Thompson - RLT Photos
2017 Yamaha Sidewinder M-TX snowmobile
The new Sidewinder is the sled that will be turning everyone’s heads this year. You better work on your hand grip before mounting this beast!
Ryan Thompson - RLT Photos
Yamaha Sidewinder M-TX: Ground Control to Major Tom
Yamaha surprised the public by introducing the Sidewinder to the mountain lineup. We’re convinced the completely new Genesis 998 Turbo might secretly be advanced warp-drive technology. Yamaha engineers (along with Arctic Cat) created a sled that generates mind-numbing speed!

Triple throttle bodies translate into a seamless throttle response with no lag in the turbo. The engine doesn’t sound like a traditional aftermarket turbo. Instead, it sounds more like a jet flying low with its afterburners on. Seriously. It is factory rated at 180hp, but AmSnow put it on a dyno with our friends at Dynotech Research, and we got an impressive result of more than 204hp, making it the first 200+hp factory production sled!   

Now, let me rein in my excitement for speed and discuss how this powerhouse handles. This 4-stroke is heavier in part because of a larger 3-cylinder engine. However, it more than makes up for the weight in the torque and power spectrum, making it feel lighter than it is.

The Sidewinder is surprisingly easy to ride; all you need is a damn firm grip! It will take you places you may be uncomfortable going. It sidehills incredibly well for such a powerful sled, with the same 36-inch stance as the 2016 Viper.  

In spots where you would normally get stuck on other sleds, the Sidewinder generates so much track speed that we joke the sled creates its own high-pressure weather system under the track, lifting it up and out. That being said, if you do happen to get this monster stuck, you better have a 5-Hour Energy drink handy because you will need both – time and energy.

We tested the Sidewinder’s climbing ability against the Ski-Doo 174, putting them both on a very steep hill with lots of powder. About halfway up the hill, there was a very steep step-up. The 174 made it over the step-up, but left a 4-foot trench. The Sidewinder, on the other hand, generated so much speed that when it got to the bench section it launched more than 80 feet up the hill, requiring our test rider to grab a handful of brake to keep from going over the top.

Along with its speed and climbing ability, the Sidewinder has a new look, and the reliability customers expect from Yamaha. Simply put, this sled is un-freaking-believable.

Summing Up
Model year 2017 offers an impressive lineup of 800+cc sleds, as well as more changes to the industry as a whole than we have seen in a long time. There is no shortage of power this year. Sleds are evolving at an amazing pace as manufacturers try to outdo each other daily.

We’re really looking forward to testing these sleds long-term under varying snow conditions. Regardless of your choice of ride this season, one thing is certain: You’ll more than likely be very happy with your choice.
Kevin Thompson AmSnow Test Rider
Kevin Thompson
Lonnie Thompson AmSnow Test Rider
Lonnie Thompson
Take 2!
The Ski-Doo 850 is easy to ride and easy to sidehill, but it does tend to wash out a little on the sidehills at times. The running boards are awesome, but I miss the foothold, which I use all the time when sidehilling. I like the narrower seat,  but it’s still wide enough to keep the roids in place. Awesome torque and power at the bottom and mid-range, but top end speed stays about the same as previous 800 models, and I expected a bit more on the top end out of the new 850.

Polaris is one smooth ride; however, the front end pushes hard in the corners on the trails. It has great top end speed, it is easy to sidehill, and has good traction when launching off the line. The stiffer lug track makes a difference when sidehilling and pulling a straight line on a hill. The clutching seemed spot on, and the rpms were always there when you needed them.
– Kevin Thompson, Test Rider

The new Sidewinder’s power is hard to match. The best way to describe it is diesel truck vs. gas. Even a turbo’d 2-stroke doesn’t have this kind of seat-of-the-pants feel. The sled feels like it will never quit accelerating. I really like the ergonomics of the handlebars. The new plastics look super sharp, and the suspension is top of the line.

Arctic Cat’s narrower running boards help improve traction on steeper sidehills. The stirrups were moved forward to help the rider initiate sidehills in technical situations. A great all-around sled, the Mountain Cat was really fun to ride and had plenty of power. It felt like it wanted to come up on the snow quicker with the new approach angle.
– Lonnie Thompson, Test Rider
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