Polaris Announces 2018 Updates To Engines, Assault, SKS And RMK

Polaris snowmobile thermostat
This thermostat was added to the Polaris 800 H.O. Cleanfire engine and will make it run cooler.

Polaris announced a series of running changes to its 2018 model lineup that will affect most of its snowmobiles for the coming winter. Most global are some changes to the 800 H.O. and 600 Cleanfire engines that power the vast majority of snowmobiles for the brand, but updates to its crossover and mountain sleds will likely have the most noticeable changes for new sled buyers. 

Starting with the 800 H.O., Polaris is switching to a new thermostat that gives the sled a lower running temperature of 110 degree F vs. the 125-degree thermostat that was previously used. This will result in more consistent engine operation and a bit more margin against overheading, the Polaris announcement said, noting that the new thermostat increases the main circuit flow by 12 percent and the bypass flow by 9 percent. The engine also gets an updated exhaust gas temperature (EGT) sensor that is said to be more durable, with improved/more durable connector and sensor element.  

Both of Polaris’ liquid-cooled snowmobile engines — the 600 and 800 — will now come with sealed cross-shaft cavity crankcases with additional lubrication and increased durability, plus an improved MAG end seal for better sealing and increased durability.

Track, Shock Upgrades

Other updates are directed at snowmobiles that are largely focused on going off-trail and churning up some powder. 

Polaris 800 SKS 146
The 2018 Polaris 800 SKS 146 will come with an upgraded Series 5.2 track.

On the popular RMK models that feature Walker Evans Monotube shocks above the skis and on the rear arm — so, all RMKs above 144 inches that weren’t spring ordered with shock upgrades — will get new shock valving with  “Hi Flow” Walker Evans pistons that Polaris says will deliver “less bottoming in the big bumps while maintaining a supple feel on the trail.”

On its SKS 146 and 800 Switchback Assault 144 models, meanwhile, Polaris is offering in-season track upgrades. 

The new SKS 146 ditches the Peak 2.25-inch track which was originally scheduled for this model and instead will come with the Series 5.2 track with the same 2.25-inch lug height. Polaris says the Series 5.2 is modeled after the modified Series 5.1 that was used by hillclimb racers last year and “provides great traction both on- and off-trail while having excellent durability.”

Meanwhile, in-season buyers of the 800 Switchback Assault 144 will now have the ability to get their sled with the Series 4 2.0 track. The 2-inch lug track was originally just a spring-order option — and, according to dealers with whom we have spoken, a very popular option for those buyers vs. the 1.35-inch Cobra track that comes standard. Models with the 2.0 track will also come from the factory with electric start.

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