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Mountain 600s

The Showcase Class

Published online: Dec 08, 2006 Feature, Snow Tests Mark Bourbeau
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We're sure that some of you faithful readers are tired of reading the SnoWest Snowtesters' enthusiasm (bunch of weenies, "Big bore is the only way to go you know") for the 600 class and its significance to the industry.
Year in and year out we feel the need to brag on the diversity yet still fierce competition that presents itself with the 600s. We also like to mention that the 600 class is the only class that has had a full slate from the Big Four-Arctic Cat, Polaris, Ski-Doo and Yamaha-every year (except 2003) since its inception clear back in 1994.
A fairly recent development that somewhat supports our attitude about the 600s comes from International Snowmobile Racing, the governing body for snowmobile racing. For 2007 and beyond, ISR has instituted the 600cc sleds as the new "showcase class" for Pro Stock racing.

Premier Showing
So, where was that premier showing of the 2007 premier class? Well, that would have been in the Upper Peninsula of Michigan. It doesn't take much brain-pickin' to figure out that mountain riders testing mountain machines in the U.P. just doesn't get the job done. Needless to say, we boycotted the manufacture/media evaluations by not joining the crowd.
We will be the first to admit that Western sales aren't the biggest slice of the pie, but at 26 percent of total sales, according to the latest exclusive SnoWest survey, the western market is an important segment for the manufacturers. It's also significant in the fact that you find very few discounted new mountain machines compared to what you find in the Midwest with trail sleds.
We can only hope that the manufacturers will acknowledge our plea and bring the new product presentations and evaluations back to somewhere in the mountains so their complete lineup may be scrutinized within each platform's intended environment-the steep and deep. We know for at least next year that will be the case. Besides that, even the short trackers look more appealing with their pictures being taken on western trails with the ever present beauty of the Rocky Mountains in the background.
The manufacturers did try to accommodate us last season with individual gigs with each sled maker.

Thankful For Leftovers
Our little change in plans for evaluating the 2007s was strung out from the last week in November with Yamaha, to the third week in March with Polaris. We tested in Idaho, Colorado, Wyoming and Utah. We also had problems with all members of the SnoWest test staff being able to make all the dates due to prior obligations or illness. Different snow conditions, different elevations, different atmospheres-you know where we are headed with this one. Absolutely no baseline for comparing these 600s as a class.
Thankfully, our saving grace is that for the first time in four years, the manufacturers bring no major changes to the table for 2007, just refinements to the 2006s.
As we detail some tech specs and rideabililty impressions, it might seem like a redundant review of last year's 600 class but there are some changes, so let's go ahead and dissect the contenders and get up to speed with what is new for you.

Arctic Cat M6
With the M5 getting the axe, the M6 is now the little guy in the M Series lineup that has everything you would want in a mountain machine. Even though our seat time on the M6 was soggy (two days of rain mixed with snow) we know how the M6 works in deep powder as the tracks (141/153), chassis and suspension remain unchanged for 2007.  Incredibly nimble but controllable; not squirrelly but quick responding to rider input.
The M6 also makes easy work out of sidehilling with its narrow and light characteristics.  If you want to pinpoint any weaknesses, it would have to be hard packed snow conditions, although this Cat has come a long way in this area, being in the third year of production. The other tick would be the forward taper on the seat.
Returning goodies for 2007 that deserve a mention would be the removable side panels on the bellypan, removable seat and hood and the saddleless plastic skis, which include an adjustable stance.
The new goods for the '07 M6 start with redesigned mountain handlebars with updated controls. Next would be the new lay-down engine design that lowers the center of gravity and helps to "centrally locate" more mass on the M6. The most important news would be the ACT Drive System with push button reverse. The Arctic Cat reverse system is mechanical (meaning the button electronically activates a gear within the ACT Diamond Drive) instead of electronic like the Doo and Polaris, where the engine stops and goes in reverse. The upside of this is that you can use the Arctic Cat system in certain sticky situations (as shown to us by our fearless guide) that you really couldn't do with the electronic version.  The down side is that this system adds about 10 lbs. to the machine.  We love the addition of reverse, but how much extra weight it adds becomes a detriment, making this feature borderline.

Polaris 600 RMK
We know we're not supposed to be comparing the 600s because we didn't take any of them out together, but the 600 RMK is one of the best sleds on the western snow-and we're not just talking about the 600 class.
Fortunately, we were able to test the 600 RMK in some of the best conditions we experienced all season long. The powder was easily 2-3 feet deep most everywhere we rode for our two days of testing, sometimes deeper. And while sometimes we were wishing we had more track (the 600 comes with either a 144- or 155-incher-we had the 144 during our ride) we were quite content banging away at hillsides and bushwhacking literally to our heart's content. We did get a chance to ride the 600 with the 155-inch track earlier in the season in Utah and we were very impressed with the new track. The snow wasn't quite as deep as it was when we rode in Idaho in March, but we were still able to see how it did in lots of different conditions from trails to hillclimbing to working in the trees to 1-2 feet of powder. The two tracks not only are different in length but in lug height (144x2 vs. 155x2.4).
To a T, each of the SnoWest SnowTest staff thought riding the 600 RMK is about as good as it gets when it comes to the smaller sleds.
And what is it that makes this ride so good? For one thing, Polaris went after its pudgy 2006 RMKs and put them through a rigorous weight loss program that saw the 600 with the 144 track shed about 25 lbs. (19 lbs. on the 155) for 2007. It simply cannot be understated just how much difference a lighter machine makes, especially in the deep powder we rode in Idaho during our big test on the RMKs. The sled pulls up easier on sidehills, it floats better on top of the snow, it is easier to get unstuck, it's easier to lay down in the powder and the list goes on. If Polaris had done nothing else to its RMKs, the weight loss alone would make the 600 worth looking at.
The Liberty twin that powers the 600 is purported to pump out 120 hp and if we had to go solely on seat-of-the-pants data, we'd say, yea, that's right. Polaris is also touting a "performance equipment partnership" with Starting Line Products with several products aimed at getting even more horsepower out of the Liberty engine. Even with that, we think the 600 RMK has got the snort to tackle most western riding situations. No, it's not going to highmark an 800, but you'll have fun trying.
The 600 also has the new Gripper ski, which is 24 percent wider than the old Sidehiller II. That's one of the reasons the sled floats like it does. Polaris has also designed the Gripper with a kind of serrated edge on top of the ski for traction when you're stuck or need to stand on the ski for one reason or another. We didn't really notice if this made a difference or not because when we rode the 600s we were in such deep powder we always had to dig down to the skis.
Although Polaris can't claim this as part of its weight savings program on the RMKs, the new cooling extrusions that run the length of the tunnel and help keep snow melted off from underneath (between the track and tunnel), make a difference in that you're not packing pounds of ice and snow. Officially, the redesigned cooling system accounts for 9 of the 25 lbs. the sled lost. Unofficially, it's got to be another 20 or more without the excess snow.
The new 155-inch track accounts for another little bit of the weight loss, which is how Polaris gets to it 19-25 lbs., depending on the model-a little here, a little there. 
It all adds up to a better ride. That brings us to the actual ride of the 600, which, once again, we'll say has the best riding rear suspension in the biz.
And that helps the 600 become a shining star in the sometimes dark Polaris skies. 

Ski-Doo Summit 600
Our mid-February ride with Ski-Doo lent to some fantastic conditions in the Colorado Rockies for powder testing. As we rode the Adrenaline 600, it reiterated the reasons why, since the move to the Rev platform, the Summit sleds have become the popular mountain machine of choice. Revered for light weight and incredible maneuverability, the Summit is the complete package-chassis, suspension, power, traction and ergos-that have helped propel Ski-Doo to No. 1 in western sales figures.
The 2-Tec 600 H.O. Rotax complements this Summit with crisp, instantaneous throttle response that has great torque making for impressive pull and bottom-end grunt.
A couple more noted favs with the test crew are the redesigned Pilot 6.9 composite skis and the fully functional running boards. On the other hand, items we found a bit annoying at times are the over grippy seat and the handlebars that seem too wide, especially when reaching across in sidehill situations.
Refinements for the 2007 Summit Adrenaline include a redesigned handlebar riser block that's much lighter and nicer looking, the MX-ZX racer seat that's lighter, a gray/black color option and the Summit X tunnel/tail light setup. The most significant change would be the Powder Max track giving way to the new 16 inch wide Challenger with 2.25-inch lugs. This added traction only enhances the already impressive powder prowess of the Summit 6. Our impression was that this old timer of the 600 class is still poised to play the rabbit through the trees.

Yamaha RS Vector Mountain
The upcoming season is the third year the Vector Mountain brings environmentally-conscious 4-stroke technology to the 600 class. Yamaha not only gives you this option for motor technology, there is also a choice to be made on whether you purchase the RS Vector Mountain or spend an extra grand and go with the RS Vector Mountain SE.
Poor basing snow was prevalent in the Wyoming Snowies during our two-day testing session with Yamaha. These extreme conditions played right into the hand of the Vector SE. The SE proved to have an obvious advantage in the deep fluff and one contributing factor to this performance variation is the deep taper, one-piece tunnel found on all Apexes.
Not only does this feature offer more running board clearance, it is lighter than its predecessor. The main beneficial component is the 16x162x2.25, 3-inch pitch Maverick track versus the 15x151x2 Challenger track. The Maverick track design is a hot commodity in the industry right now and it most definitely made a big difference between the two RS Vectors.
The SnoWest crew feels the Maverick track as a near necessity for the RS Vector's most notable hindrance-weight. The Vector tips the scales at nearly 100 lbs. more than the three competitors in this class and the powerful 120 Genesis 3-cylinder simply can't cover that large a deficit.
On our needs (more or less) list is the snow accumulation and lack of traction on the running boards and the windshields being purely cosmetic.
We love to rave about the Yamaha's finish and detail, creature comforts that have a "Lincolnesque" quality. A comfortable, functional seat with (still) a storage trunk; hooked handlebars that have been raised another inch with the just right height, width and location for the ultimate in comfort and leverage; aggressive, high flotation plastic skis that work great with the chassis and have a simple-to-change adjustable stance and tricked out instrumentation and controls.
The RS Vector SE is as smooth and stable as any snowmobile you will have the pleasure to ride.

In A NutShell
After our seat time with the 2007 600s, we still applaud this premier class and consider these machines "high return" purchases. They are so easy to peg out the fun meter, with getting the most out of your investment without having to have nads the size of grapefruits. Cheaper initial investment and operating costs than that of their big brothers make for a great acquisition for intermediate to expert riders. And the 600s aren't a bad way for those new to the sport to get a start. They certainly aren't intimidating and as your experience grows, so does the capability of the 600s.