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The weight lossSo where did Polaris come up with all the weight savings and what's different on the new RMK?
First, the chassis is considerably different and uses a structurally bonded (glued) aluminum chassis with a two-piece cast bulkhead, like Rush. Polaris claims that not only is the new chassis lighter but 300% stiffer than before. The 800 Cleanfire engine is roughly the same, aside for some minor tweaks and mapping changes.
The rear suspension is lighter because the torsion springs have been removed. However some weight has been added as Polaris has ditched the air shocks and gone back to coil-over spring shocks. Polaris says this change is for better bump control and balance. The rest of the weight has been saved with a bunch of small savings, for example the running board rail that was steel is now aluminum, the rear bumper is made from carbon fiber and the seat support is aluminum. More weight was removed via new narrower tunnel cooling extrusions.
Polaris also has created a purpose-built RMK brake system with Cyclone master cylinder and lightweight single-piston caliper too.
While there are plenty of changes, many of the proven RMK parts from the IQ-based model, such as its track, engine and skis, remain for 2011.
Polaris tells us part of the design criteria for this model was to lighten it while retaining the good balance and handling that the IQ RMK had become known for.
Our initial impressions from riding the new RMK for several hours in Utah is that the machine climbs and moves through snow much better than before, and despite few engine changes the machine feels a lot more powerful. (probably due to a better power to weight ratio.) While we love the weight and climbing ability of the new RMK, after our initial ride we were not totally sold on the handling of the new machine yet but only had limited time on it. The new riding position and the PRO-RMK's tall wide Pro-Taper handlebars sometimes make it feel more like a REV-XP and a tad harder to control than the old RMK.
Our handling concerns could be due to the setup on the prototype machines we rode and bad snow conditions. One thing we know for sure is that when it comes time to ride the 2011 machines from all the manufacturers later this spring, the RMK will be a top priority.