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2016 4-Stroke Sleds for Mountain Fun

Climb the hills in a Yamaha SR Viper M-TX or an Arctic Cat M-series snowmobile
2016 Arctic Cat M series mountain sled snowmobile 4-stroke
Completely redesigned front suspension, spindles and skis make throwing the M sleds onto one ski and sidehilling easier than before.
Stephen W Clark
The very nature of 4-stroke engines makes them more expensive to develop and manufacture. Complexity comes from added components in the valve train and the use of exotic materials and manufacturing techniques to try to reduce the weight of an engine that simply has more to it than a 2-stroke.

In the grand scheme of things, our snowmobile industry is really small and unfortunately doesn’t have the sales volume to justify the massive spending it takes to develop technology exclusively for the snow.

So it’s no surprise that the only two 4-stroke engines available in a mountain snowmobile are built by the big Japanese powerhouses of Yamaha and Suzuki, using numerous parts that cross over from other powersport vehicle engines.

Just the two of us
Arctic Cat and Yamaha are the only two manufacturers who have 4-stroke mountain sleds, and their supply agreement is in full swing. Both manufacturers are using Cat’s ProClimb, the chassis in the Yamaha SR Viper M-TX models, and Arctic Cat M 7000 and M 9000 models. Essentially, there is one chassis and two engine choices. If you buy a Cat, you can get their Suzuki-built 1100cc turbocharged twin cylinder engine (their 9000 motor) or you can get the Yamaha-built, naturally aspirated 1050cc triple (labelled 7000).
2016 Yamaha SR Viper M-TX mountain snowmobile 4-stroke
Stephen W Clark
2016 Yamaha SR Viper M-TX mountain snowmobile 4-stroke
BIG POWER! The dealer-installed MPI turbo kit turns the SR Viper from mild to wild! Ripping up to altitude or down to the flats, this sled has guts!
Stephen W Clark
Yamaha offers just their 1050cc triple Genesis motor in their SR Viper, and all Yamaha sleds come from the factory naturally aspirated. However, many of these Yamahas end up being turbocharged via the dealer before they are delivered to the customer. There is an agreement with the turbo company MPI that allows their turbo kit to enjoy a “Yamaha OEM approved” status, and many are sold through the Yamaha accessories department. It is especially heavily incentivized during the spring buying season.

The good news for buyers in the mountain segment is that this one chassis received a pile of updates for 2016. The front end of the machine has been completely redesigned with new spindles, a-arms and skis. The result is a narrower 34.5-38.5-inch ski stance, a 2.4-pound weight reduction and a significant improvement in sidehill handling. In addition to the front end, there are small changes to the rear suspension to make it function better.        

While many parts cross over between the Arctic Cat and Yamaha models, there are a few unique components that differentiate them. The Yamaha has different clutches and slightly different-shaped plastics, but for all intents and purposes, they are nearly the same thing.

Navigating the vast number of models and different configurations offered between Yamaha and Arctic Cat is no easy task. Multiple track lengths are available, but the engine choice is really the biggest factor, and the major debate in that decision is whether to ride a turbo sled or a naturally aspirated machine. Everyone loves the power of a turbo and thinks they ABSOLUTELY NEED a turbo, but the reality is not every rider belongs on a turbo. It is really important to note that the performance difference between a turbo and non-turbo is around 60 hp, which is a huge difference. To put it bluntly, a naturally aspirated 4-stroke is not the kind of sled you are going to use to go climb glacial chutes in Revelstoke, British Columbia.

Pros and cons of different 4-strokers
Each of the powerplants has its own strengths and weaknesses. The stock Yamaha (or 7000) engine only produces around 125-130 hp, but it will run forever and is the most affordable. The Cat Suzuki 9000 engine makes good power, but it isn’t quite as refined as the Yamaha engine, yet it does offer the reliability of a factory turbo. It’s expensive though, and the accessory turbo version of the Yamaha actually makes a little more power. In our experience, the factory-approved turbo kit from Yamaha has the most scope for tuning, but it’s truly an aftermarket turbo, so it’s not quite as easy as the other two options. Plus, it’s the most expensive option.
2016 Yamaha SR Viper M-TX mountain snowmobile 4-stroke
SR VIPER – Good: Sidehill handling improvements, big horsepower turbo kit available, no adding injection oil. Bad: Not as much innovation as we see from other OEMs in the mountains, still heavier than we would like.
Stephen W Clark
2016 Arctic Cat M series mountain sled snowmobile 4-stroke
M 7000 & M 9000 – Good: Sidehill handling improvements, twin (9000) and triple (7000) cylinder options, factory turbo power (9000), no adding injection oil. Bad: M 9000 is pretty darn expensive, still on heavy side of the hill.
Stephen W Clark
Picking your powerplant will also somewhat dictate your choice of track length. Longer tracks are obviously more effective on the big horsepower machines, and in the case of the Arctic Cat 9000, the only option is a 162-inch track in either a 2.6-inch lug with the Sno Pro or a 3.0-inch lug on the Limited. Yamaha, on the other hand, offers more options, ranging from the 141x2.25-inch PowerClaw on the SR Viper M-TX 141 SE all the way up to the 162x3.0-inch on the SR Viper M-TX 162 LE, and just about every other conceivable track length in between. The real wildcard sled in this category is the 141 Viper. We rode this sled with the MPI turbo, and you would be hard-pressed to find a sled that will go faster, do as many wheelies and generally be as much fun to ride.

The 4-stroke end of the mountain segment is becoming increasingly stagnant these days, and it would appear the hints at early innovation we saw from Polaris and Ski-Doo in the 4-stroke mountain segment are over. However, on the Yamaha side of the 4-stroke coin, the motorcycle business is on the gas, launching multiple new models per year and bustling with class-leading technology. Unfortunately, it would seem the snowmobile division has been cut off to some extent and stuck with older technology. The majority of the advancements seem to be coming from Yamaha’s supply partners in Thief River Falls. We realize it’s all about dollars, but one can only hope things will change so we can see Yamaha return to a position at the front of the snowmobile market, where it ruled in the late ’90s and early ’00s.

Buyers in the market for a 4-stroke mountain sled have a lot of options available to them between Yamaha and Arctic Cat. Both have their own boost options, and the Cat M 7000 Sno Pro and Yamaha SR Viper M-TX SE models are typically priced the same or within a few hundred dollars of each other. There are lots of options and good machines for the right buyer. Just make sure you do your research and purchase the right machine for what you are doing.
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