Building a Mountain Sled

No bells and whistles-just performance and handling

November 2006 Feature Steve Janes Viewed 1160 time(s)
Once upon a time a young snowmobile engineer was test riding his model X design in the rugged mountains of western Montana when he came upon an old snowmobiler who was highmarking on a steep, north-facing slope. The young engineer watched for a few minutes as the old snowmobiler rode his sled high up the slope before gracefully turning out and cutting across the face before descending the slope.
When the old snowmobiler stopped to let his sled cool down while he got a drink of water, the young engineer decided he would take his fancy "state-of-the-art" model X sled up the steep slope. However, try as he might, the young engineer could not reach the heights obtained by the old snowmobiler.
The engineer rode over to where the snowmobiler was resting to see what kind of performance-enhancing products were added to the snowmobile the old man was riding.
The sled didn't look like anything special. In fact, if anything, it looked more like a stripped down version of a model X sled-some of the plastic "fit and finish" that came on that particular model had been removed, the skis were different, there was just nothing fancy about the sled.
"So what have you done to this thing?" the engineer asked.
"Not much," the old man replied. "Little engine work to clean up the laziness; lighter pipes, some bracket changes in the suspension. Mostly just freeing up some performance by eliminating some unnecessary weight."
"Mind if we swap sleds and ride for a few minutes?" the engineer asked.
With that, the two exchanged snowmobiles and headed across the slopes in search of a new hill to highmark. But as the young engineer was riding, he couldn't believe how easy the older sled handled. It would pull up on the side with the slightest effort. It was responsive to the throttle, making the handling seem so much better than what the engineer could remember. The older snowmobile was fun to ride.
After a while, the two stopped to exchange thoughts.
"So this is supposed to be the new and improved?" the old man asked.
Sheepishly, the young engineer responded "Yes, this is what I'm designing for next year's model."
"Well, it's certainly a pretty sled.but it ain't for me. Looks like I'll be riding my old sled for another season," the old man exclaimed before saying good-bye and riding off.
The young engineer sat there for a few minutes, mulling over what the old snowmobiler had just said. That afternoon, when the young engineer returned to his shop, he just couldn't get the words "it ain't for me" out of his mind. He also couldn't forget the sensation of control he felt when riding the old snowmobiler's sled.
"What if I changed this, or removed that?" the young engineer pondered as he studied his state-of-the-art snowmobile. And before he knew it, he had worked throughout the night, removing parts, changing mounting points, modifying exhausts and basically doing everything he could to make his sled something the old snowmobiler would want.
When he was done, he looked over his design and thought to himself, "The boys in marketing aren't going to like this.but that old man might." And after a few minutes of test riding on the snow, he knew he had finally built a true mountain sled.
When Polaris engineers went about designing the new Dragon RMK for 2007, they recognized that the sleds they were seeing in the mountains weren't the same sleds they were designing for the dealers. The sleds that were marking high on the slopes were "purpose-built." They resembled stock sleds, but they were lighter, better-handling and had a little more power.
Polaris realized if it wanted to recapture its market position, it needed to stop wasting time designing sled parts that didn't do anything except enhance the looks and add weight. It needed to focus on three key elements-power, weight and handling. Just as the mountain sleds have been purpose-built for conquering the steep and deep, so are the 2007 Polaris RMKs. Gone are the plastic parts added to conceal brackets and bolts. If it doesn't add to performance, it's not added. And it's called RAW.

Class Act
Now before we get too far into explaining the attributes of the Dragon RMK, we need to point out that this story is actually about the best new 700 class snowmobiles for 2007. And without reservation, we will state the Polaris Dragon RMK stands alone at the top of the 700 class. But on a side note, it's also the only 2007 sled in the class. But before you jump to any conclusions, let it be known that this sled is total class.
With that said, the Dragon RMK represents a retro in modern technology. Much like the sleds of the 80s, Polaris engineers didn't try to hide mounting brackets, welds or bolts. It has a bit of that "unfinished" look, much like most of the mod sleds you see on the mountains today. Its design focus was to be functional, not fancy. It eliminated the parts that usually end up either getting removed by the rider.or eventually falling off and not getting replaced. The plastic junk that serves about the same purpose as a bad hair piece-a feeble attempt at vanity. Only this time, Polaris engineers were less concerned about what it looks like on the showroom floor and more concerned with what it performs like in the steep and deep.
What they accomplished, in the eyes of the hard-core mountain riders, is a work of art-a purpose-built sled with a rugged look and a sleek, lightweight design.
Last winter we had two opportunities to pound on the RMK Dragon in rugged terrain. Our first shot at the Dragon was in some deep Utah powder in mid-January. And our ride wasn't an orchestrated ride through sun-baked powder where everything works well. It was a big time boondocking ride up one ridge, down another, through the trees, across ravines, down canyons and about everywhere else imaginable. We weren't looking for easy lines. It was more of a "let's see who we can scrape off in the trees and bury in the creeks" type of ride: survival of the fittest.
And we must admit, after several hours of full-throttle bushwacking aboard the new RMK 700, we were impressed. This wasn't the same sled as the 2006 RMK 700 (which was actually a 755cc sled trying to be shoe-horned into the 700 class to compete with Arctic Cat's M7). This was an all-new model.the kind of "all-new" that make snowmobilers who have been around the industry for several decades stop and marvel at some of the design innovations.
Even before we fired it up for the first ride, we were intrigued by the five-piece tunnel and new cooling system. The straight lines of the new tunnel, the swiss cheese holes in the running boards and the bare bars under the seat and at the rear of the running boards made the sled look like something the freestylers would be hitting the ramps with.
Once on the snow, the Dragon didn't handle like a huge fire-breathing monster, but rather like a gazelle-quick, light and graceful.

Passing The Test
Some same first impressions are lasting impressions. Our first impression of the Dragon was very positive. We boondocked, bushwacked, tree bashed and pounded the slopes. We got stuck, fell off and rolled over. We were bruised, abused and bloodied; scraped and scratched. We rode them like we stole them. And at the end of the day, we were tired, sweaty and sore. But the sleds didn't disappoint.
Two months later we got another opportunity to ride the Dragon for a couple of days in Island Park. The snow was deep, heavy and challenging. And we tried to make the Utah ride look like a trail ride compared to the terrain we pounded through here. Shovels and saws were mandatory on this ride.
The first day we pounded the terrain around Mt. Jefferson, basically focusing our attention on the state line ridge and down into Rock Creek before dropping off the waterfall and heading over to Red Rock Pass area. On the second day, we headed up toward Two Top from Garner Canyon. Midway up, we turned southeast and started breaking through the ridges before eventually working down a drainage to Meadow Creek Resort.
There were times when all seven of the sleds we had out were scattered and stuck amongst the tall pines in the deep canyons. It was sort of a "fend for yourself" experience when it came to picking your lines through the trees. The best description of where we were heading was "that way." We may not have known where we were going.but we knew when we got there-the view was always better.
We kept having to remind ourselves that we were riding 700s. They had the power of 800s and the handling of 600s. They had a friendly powerband and impressive bottom end and midrange. They continued to pull hard going up steep slopes, yet pulled up on one ski easily when cutting a sidehill.
In our view, there are three criteria when defining a mountain sled-power, weight and handling. The Dragon receives high marks on all three areas.

The Dragon is powered by a 700 HO Cleanfire engine based on the 600 crankcase with peak horsepower (140 hp) at 8250 rpm. The changes to this small block engine include a larger flywheel and ignition for the battery-less system, plus a lightweight exhaust. It offers a crisp, powerful low end while maintaining more horsepower longer on the top end. The Cleanfire engines found on the 700 are about 15 lbs. lighter than last year's 755.
The 700 HO is clean, reliable and self-calibrating (adjusts to changes in temperature, elevation, engine temperature, exhaust temperature). The Cleanfire injection system uses four injectors-two in the cylinders, two in the crankcase, for an efficient burn that is 43 percent cleaner than the industry baseline. This also improves fuel efficiency for more miles per tank.
The built-in safeguards that enhance reliability include: digital CDI, Throttle Position Sensor, Water Temperature Sensor and Detonation Elimination Technology. Another subtle change is a cleaner routing of the fuel line that eliminates some of the pulsation and fluctuation in fuel distribution. And the Dragon comes standard with Polaris Electronic Reverse Control.
With the new engine comes a new cooling system and tunnel-both integrated into a unique and "outside-the-box" way of engineering that has changed the way of designing snowmobiles.
In the new cooling system the perimeter cooling and radiator have been replaced with unique extrusion cooling that runs the length of the tunnel. Not only does this eliminate 9 lbs. of the dry weight of the sled, but it also eliminates snow buildup on the underneath of the tunnel which can add several pounds of ice over the course of a ride. The cooling system has led to the creation of a new five-piece tunnel that Polaris engineers claim will increase the strength of the tunnel.
To finish things off in the topic of power, while introducing the topic of weight, the Dragon will feature a new LWT Team secondary clutch that is lighter and more efficient. This means you have about a pound less rotating mass. 

For something that normally would be an absolute, when it comes to weight (or lightweight) for snowmobiles, the concept becomes relative. After all, when we're in the 500-pound range, what is lightweight?
Polaris expects the Dragon manages to dip below the 500-pound mark-somewhere around 484 lbs. dry. Naturally, until the sled actually rolls off the production line and we put it on scales, we can only suspect that this mark is an obtainable goal.
But numbers aside, we do know how the Dragon feels on the snow. Is it light? No. (We don't necessarily believe any production sled is light.) Is it lighter than last year's RMK 700? Definitely. Polaris projects about 50 lbs. lighter. Is the weight proportionately distributed? Absolutely.
The combination of weight reduction and balance distribution has made the Dragon a very friendly sled both on the trail and in the powder. Since we'll get into the balance distribution later, for now let's examine how Polaris plans to shed the 50 lbs.
First, if you go back to power, we said Polaris took 15 lbs. off the powertrain. Well, a lot of that could be attributed to a lighter exhaust system. Some goes to the fact that the 700 is based on a small block. But a pound here, two pounds there, on the nose of the snowmobile really helps to lighten up the front end.
Next, in the chassis, Polaris anticipates about a 25-pound reduction. Some of this (9 lbs.)  goes to the new tunnel design that eliminated some of the cooling requirements. Some (5 lbs.) goes to the change in the handlebars which we'll discuss later. Some (6 lbs.) goes to the new Series 5 track. And the rest goes to the process of eliminating needless parts which produced the RAW look.

If there's one thing Polaris engineers pride themselves with, it's handling. Polaris snowmobiles have always been great handling sleds. So when the IQ chassis was first released and when the consumer started having fits with the temperamental handling qualities (sometimes the sled would just dip or dart on you, making it somewhat of an adventure to ride), Polaris realized that somewhere there was a flaw in the design.
What they found was that the rider position had everything to do with the balance point of the snowmobile. If the rider sat far forward, it put too much weight to the front of the sled. To correct this, Polaris had to make some significant design changes to the RMKs.
First, the Rider Select Steering had to go. Most mountain riders were standing the bars straight up and that moved the weight too far forward. The reason riders moved the bars forward was to get more height. The simple solution to this, which also resulted in a five-pound weight reduction, was to just build taller bars and go back to a fixed steering post. The taller bars allowed them to use a shorter post while still gaining overall height in handlebar position. And since the bars are aluminum and the post is still, and since aluminum weighs less than steel.well, you can do the math.
The bars are still adjustable during pre-ride setup. And there are actually three riser blocks available. The riser block that comes stock is 3.75 inches. There are two accessory blocks available-2.5 inches and 5.25 inches.
The second major change to the balance point of the sled was in the rider sitting position.or more specifically, where the foot rest was located. By simply moving the foot stirrup back a couple of inches, it kept the rider from getting his weight too far forward.
And since the changes in the tunnel altered the angle of the tunnel taper, Polaris had to redesign the seat and fuel tank. This allowed them to match the seat with the footrest and handlebars, thus moving the rider back while maintaining a natural feel to the sled. In the deep powder, you really appreciate the balance.
But what about the time you spend on those mountain trails riddled with moguls? Sure the balance will help you stay level and in control. But Polaris engineers went an extra mile, taking handling to a new level with Walker Evans Air shocks on both the front and rear.
In a section of whoops, we found that you could stand on the Dragon, grab the throttle and fly through the bumps with little effort. The Walker Evans Air shocks literally sucked the energy right out of the bumps.
The final piece of the handling puzzle comes in the form of new skis. Named the Gripper (because of the traction design on the top of the ski), these skis are designed a little wider and with a deep single keel. The width will help with flotation in deep powder. The deeper keel helps it to steer better in all types of snow conditions. The traction top means.well, if you ever have to stand on a ski to get the front end flat in the snow, you know what we're talking about.
The skis are designed with spacers on the mounting plate to allow adjustability between 39-, 40- and 41-inch ski stance.

Finishing Touches
If you're not sensing that the Dragon is an entirely new beast, here are just a few more major and significant changes.
First, the new tunnel comes with a new taper and new running boards. Polaris has turned what used to be a one-piece tunnel into a five-piece rear platform that incorporates cooling while reducing weight, increasing rigidity and providing a better standing/riding platform. In one quick shot, Polaris engineers achieved a lighter, stronger, more practical tunnel.and with a side effect of more fuel capacity (11.5 gallon fuel tank) and a clever "quick attach" saddlebag/accessory rack system-bonus.
This allows for two T-slots along the top of the tunnel behind the seat that allows the rider to easily bolt extra fuel or luggage to the tunnel.
The running boards are wider in the rear for more foot room and are punched with one-inch holes, giving it a "screened" effect which allows for easy removal of snow buildup. The back of the running board has an open bar-allowing the rider to kick snow back and stomp it forward to remove snow. This bar is also at a location where the rider can work the throttle and pull the back if needed to get out of a hole.
Next there is the new Series 5 155-inch track with 2.4-inch lugs. The track is 6 lbs. lighter, which means less rotating mass. It is designed with a larger pitch (the spacing between the lugs) and larger windows for the drivers. Polaris has added a center driver (and holes in the middle of the track) to eliminate ratcheting.
This track works well to keep the sled up on the snow and reduce some of the trenching that occurs in deep snow. Also, a new rear idler design (going from three wheels to two, the idlers have been tucked inside the rails) gives the track some flexibility on the outside edge that can facilitate sidehilling.
The 2007 Dragon exemplifies the concept "purpose-built" and promises to regain Polaris' reputation of quality and reliability. And the more we rode it, the more we realized we were riding a classy sled-a sled the old snowmobiler would want to ride. 
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