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Mountain 600 Class

Stimulating the senses

Published in the December 2008 Issue Published online: Dec 10, 2008 Feature, Snow Tests Mark Bourbeau
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The sport of snowmobiling is winter recreation which stimulates all five of the human senses and then some. Yes, that's right, all five.

The 2009 class of 600 mountain machines represented by the Arctic Cat M6 153, Polaris RMK Shift 144/155 and the Ski-Doo Summit E-TEC 146/154, along with the Everest 146 is the pillar of affordability for experiencing this invigorating, high performance stimulus.

These spunky 600s are at the low end of the industry's high performance spectrum with a class average of 120 hp. That's seemingly unformidable for power mongers and speed freaks, yet obviously adequate enough power at an impressive class average of around 3.9 lbs/hp. Compare these numbers to the "premier" 800 class, where the weight-to-horsepower ratio is in the neighborhood of 2.9 and yes, there is sufficient performance in the 600 class, far more than some enthusiasts might want to come clean about or even admit to.

Can't You Smell That Smell?

That once-upon-a-time, over indulgent odor of rich 2-stroke smoke associated with snowmobiling is becoming less and less year by year, acting as more of an intoxicant rather than a deterrent (especially for us old timers). With the ever tightening numbers from the EPA for emissions standards-requiring a fleet average of 50 percent reduction in hydrocarbons (HC) and carbon monoxide (CO) by 2010-the manufacturers are "cleaning up" their act.

At one time, the thought was directed toward 4-stroke technology as the only answer to exorbitant air emissions, but recent 2-stroke technology is gaining ground at a rapid pace as this 600 class exhibits with some ground-breaking concepts.

The 2009 Arctic Cat M6 returns basically unchanged in the motor department. Still powered by a Suzuki 599cc liquid-cooled twin with the venerable batteryless EFI, an Exhaust Pipe Temp Sensor working with electronic APV exhaust valves to help regulate and hit optimum pipe temperatures, which, in turn, optimizes performance and helps with emissions reductions. This sled's performance "Still has linear power down low, but seems to spool up quicker than in years past," said one SnoWest SnowTest staff member, while another said, "Excellent power for a 600."

Some bigger news is that Polaris has dropped the carbureted model (too bad for you tinker tuners) from the 600 lineup for '09, making all Liberty powerplants Cleanfire injected now. Some cream cheese icing on top of this homemade carrot cake is that the four-injector system has also disappeared for a new two-injector system. This effort was taken not only to clean up the less-than-stellar performance in the transition mode of the four-injector system, but to also make advancements in meeting the much tighter 2010 EPA emission regs while improving fuel economy. The lower crankcase injectors have been removed and now all the fuel is delivered via two transfer port injectors. Power is still a solid 120 horses, down only slightly. A couple of SnowTest riders said, "now the best all-around power package in class" and "new Cleanfire-2 system definitely helped the performance."

The biggest news-maybe even for the entire industry in 2008-09-is the new Rotax E-Tec 600 H.O. Welcome to a new generation for lighter weight 2-stroke engines with sophisticated electronics and innovative technologies, already proven in BRP's Evinrude outboard engines. This technology is also award-winning, earning the Clean Air Excellence Award from the EPA, as well as several leading consumer satisfaction awards.

With the E-Tec, fuel is directly injected into the combustion chamber at extremely high pressure (500 psi) after the exhaust port is closed, all with amazing precision. The end result is the cleanest 2-stroke snowmobile engine ever produced, even cleaner than some of the competitive 4-strokes, according to Ski-Doo figures.

This Rotax E-Tec 600 is built on the familiar H.O. bottom end. It is fitted with high voltage electronics to power the injectors and its brains, along with the new cylinder head which houses the platinum-tipped spark plugs that are warranted for three years and up to 6,600 miles. Also in this new head are voice coil injectors. Add to this the 3-D E-Rave power valves, and this 600 will get at least 20 mpg with virtually no smoke or smell and half of the oil consumption when compared to the current industry benchmark 600 H.O. SDI engine. The EPA's Normalized Emissions Rating of 2.6 for this engine is well below that of its closest competitors, which just happen to be its sibling 600 SDI as well as the Polaris 600 CFI.

Not only is the 600 E-Tec clean, quiet, economical and lightweight, it has an automatic summarization function and is claimed to start in one pull every time, which we can attest to after four days of evaluations.

And speaking of evaluations, we did experience a throttling/engine performance snafu that Ski-Doo reps guarantee will be resolved by production runs. Other than that, SnowTesters remarked, "Darn good performance for brand new technology," and "motor is snappy and pulls hard." Another comment was, "Ran good the whole way through, felt competitive in class even in its detuned state," referring to the 600 SDI motor.

Can You Hear Me Now?

Better all the time. With engines and the EPA still in mind, another aspect of snowmobiling that has progressed from an accepted nuisance for many, to a stimulating side effect, would be the noise factor. Once again, the EPA (in conjunction with the Snowmobile Safety Certification Committee) runs a tight ship with its Noise Pollution Acceptance Level regulations, which just happens to be 80 decibels maximum at wide open throttle (under controlled testing conditions).

We had no equipment to conduct our own scientific NPAL test to determine if any of the 09' 600s are pushing the upper limit, but all eight of our ears tell us that this is a fairly quiet threesome. The current factory installed and tuned air intake and exhaust systems, coupled with some other sound deadening technology, muffle these 6ers to a tolerable, enthusiasm-bolstering 2-stroke whine that is like music to the ears of many an aficionado. There is no 4-stroke rumble in this class, although the Summit's E-Tec 600, thanks to its stratified and homogenous fuel system technology, is not only a petro and oil stingy engine, but also the quietest 2-stroke to date. "Still sounds like a 2-stroke up on the Rs, but nearly silent and oh so smooth at idle and lower rpm . very similar to a 4-stroke," one SnowTester said.

Doctor Feelgood Times 3

In order for these ponies to be able to deliver a stimulating comfort level for the jockey, there are three main factors that comprise that "comfortable feeling" both on and off the trail. Weight, suspension performance and rider ergonomics are the most critical individual components to achieve a high comfort level, and must also complement one another for the complete package.

As we alluded to earlier, this class' average weight-to-horsepower ratio is only around a pound more than the 800s . a respectable stat in itself, which led one SnoWest rider to say, "These 6s are simply fun to ride with good, useable power." Projected manufacturers' dry weight figures show the Ski-Doo Summit E-Tec 154 in X trim bouncing the scales at a scant 422 lbs. (lightest liquid-cooled western sled in the industry) and the Arctic Cat M6 153 is near the top end of the class, weighing in at 472 lbs. That is around 14 lbs. less than the `08 M6, however. The Polaris RMK Shift 155/144, followed by the Ski-Doo E-Tec 146 and Everest 146, fall into the weight lineup (high to low) respectively.

That high comfort or "sweet spot" that the SnoWest crew look for in a sled's stability and handling is more of an all-around setup that performs well in powder snow and on hard pack snow, although, obviously for us, we lean more toward the off-trail mannerisms, but all in an aggressive fashion.

With this in mind, our favorite feel was the RMK with what one SnowTester described as, "Stable yet agile in all situations" and "Very good over-all package for predictable stability and handling." Exploration of this sled's suspension/chassis combo reveals a handlebar setup and skis that score high across the board with the team and a seat that is without a doubt the best in class and maybe even, "Currently the best in the industry for mountain riding," according to a couple of testers.

The RMK's weak link is its running boards. With feedback like, "The running boards are the worst in this class," we can live with the width and traction available, but snow buildup and evacuation is marginal at best, only compounding the width and traction concerns. Even with the running board issue, a team member tells the tale of the RMK as being, "A good all-around machine that inspires confidence. You're never worried that it's going to get away from you or surprise you in any way . it's very predictable."

The Summit 600 is new in the XP chassis this year and for unconfirmed reasons the SnoWest crew struggled to find the "comfort zone" while riding the protos at evaluations. Suspension performance and ride quality were good but the handling demanded our undivided attention (we have a tendency to get distracted on occasion). One SnowTester said, "Over aggressive handling. I really can't ever relax," while another said, "I'm not confident in what it will do and when." We also agreed that the Rev XP platform is "too stable or neutral" for easier powder play and sidehilling in the more extreme conditions. One tester said, "When you tip the Summit up, it just wants to correct itself and sit back down, which is a good thing for the average enthusiast."

Creature comforts on the Summit 6 rank high with the team, as one tester said, "One of the best overall handlebar packages in this class." Another said, "Well-designed running boards with excellent traction." He added, "I love the seat but it could be narrowed up a tad."

With the M6, we claim the M stands for mountain minded . right up our alley. Yes, the M6 is strong with its inherent off-trail or on the snow characteristics as some testers observed. Comments such as, "Handles great in the powder but bounces around on the trail," "Love it, easy to hold a line on a sidehill," "Excellent powder sled with the new tunnel and track," and "Bump ride continues to improve but still a little on the Po-Go side" came in after our rides in Grand Lake, CO.

With all the boondocking genes that are bred into this Cat, some of its rider ergos don't support these attributes. The handlebars are keepers, they just need to be taller for better leverage. The seat is also too low for quick and easy sit/stand transitions. But there is a possible solution to these issues as Arctic Cat dealers will have access to a Boss seat option and the Sno Pros are coming with the all new Vertical Speed Bars, both of which can be bolted right on your M6.

Two improvements for `09 that deserve attention are the running boards and tunnel. "Really like the brace at the back for footing traction and leverage," one SnowTester said, while another commented, "Well designed with superb traction."

Eye Can See For Miles

The M6, RMK and Summit are all visually stimulating. Each is an attractively designed machine in its own right, whether it's the sharp-edged, "faceted" design of the Ski-Doo, the smoother, more flowing design of the Cat and Polaris or the monochromatic look of the Polaris. A couple of perks to the plain Jane look of the Shift is a less expensive initial investment. And, if you don't like looking totally stealth, then it's called personalization with graphic packages. Several can be acquired through your Polaris dealer.

These ponies provide a double hit of eye candy by not only looking good, but carrying you to unbelievable natural visuals. With the power and flotation to get into the backcountry scenery and up on the high country vistas, if you are new to the game, don't forget your camera.

Satisfying The Hunger

Taste and hunger. It's all the same thing, right? If you hunger for and need a fix for excitement and exhilaration (not necessarily adrenaline), these 6s will satisfy. The final component that adversely affects the overall package and go ability of this little "high-po class" is the track.

It's hard to argue against the class-leading floatation delivered by the 16-inch wide Powder Max track on the 146 and 154 Summits (the 500 SS or standard Summit 146 sports a new 15-inch wide Maxer with 2-inch paddles).

But then there's Cat's new track, which elicited comments like, "The new Power Claw track for the Cat is a work of art" and "Favorite OEM track yet." The Power Claw was definitely a favorite among the SnoWest staff.

When it came to the Polaris track, one SnowTester said, "I would opt for the 155 over the 144 for the extra flotation and the improved 5.1 design." Polaris' 155 is the longest in this class.

Obviously, with those kinds of options-almost a buffet-there are numerous opportunities to fulfill that hunger. On the other hand, if you have a hankerin' for the taste of blood, you best be on top of your game unless you are playing with other 600s.

If you are really demanding and need actual taste bud satisfaction, that is taken care of with the aftermarket exhaust cooker that you have installed on your new Artic Cat, Polaris or Ski-Doo 600 that's loaded with hot bratwurst, fried chicken or burritos for lunch.

Mission Complete

With all of our senses having been stimulated during new product evaluations, it's awful hard to pick a class winner as there isn't a "runt in the litter."

One staffer's final thoughts were, "Overall, I think the 600 class is a fun class. We took those sleds into the steep and deep and had a great time. Sure, they won't make the high mark against the 800s, but I was having so much fun on them I didn't care. Aside from climbing the really tall stuff, we took those sleds anywhere we would normally ride. They might be a little more work in the really deep powder because there is a little less power and the tracks are smaller, but we sure had fun on them. And we couldn't have asked for any better testing conditions . we took them through the paces."

The SnoWest test staff will give a double nod in this class, one to the Polaris Shift RMK 144/155 for the best overall seat-of-the-pants feel and bang for the buck with the other to the Ski-Doo Summit E-Tec for innovation beneficial to the sport and industry in general while being a potential class leader.

GeneralArctic Cat M6Polaris 600 RMK ShiftSki-Doo Everest 600 (Base) Everest 600/X
Age of this model Fifth year Second year First year
Powerplant/Powertrain
Engine Suzuki Liberty Rotax
Displacement 599cc 599cc 597cc/594.4cc/594.4cc
Cylinders 2 2 2
Carburetion 46 mm throttle body batteryless EFI Cleanfire Injection (2) 2 TM 40/Electronic DI
Primary Clutch Arctic (rpm sensing) P-85 TRA VII
Secondary Clutch Arctic (roller cam) ACT drive system P2 QRS
Drive Sprocket 8-tooth drive 8-tooth drive 8-tooth drive
Chassis/Suspension
Chassis M IQ Rev XP
Front suspension AWS VI double-wishbone A-arms IQ RMK Adjustable Dual A-arm
Front shocks FoxZeroPro gas and adjustable preload springs Ryde FX Motion Control/Kayaba HPG/Kayaba HPG T-A Aluminum
Front travel 9.2 inches 9 inches 9 inches
Rear suspension ACT M Series slide rail RMK SC-5M
Rear shock Fox Float Ryde AFX Motion Control/Kayaba HPG/Kayaba HPG T-A Aluminum
Rear travel 18 inches 14.5 inches (144)/15.5 inches (155) 14 inches/14 inches (154)/15 inches (163)
Center shock Fox Zero Pro IFP Ryde FX Motion Control/Kayaba HPG/Kayaba HPG T-A Aluminum
Ski UHMW plastic saddleless Gripper Pilot 6.9
Dimensions/Capacities
Dry weight 472 lbs. 469 lbs. (144)/484 lbs. (155) 425 lbs./435 lbs./422 lbs.
Track Power Claw 15x153x2.25 Series 4 15x144x2.0/Series 5.1 15x155x2.4 15x146x2/16x146x2.25/16x154x2.25
Ski stance 39-41 inches 69-41 inches 40-42.5 inches
Fuel 11.4 gallons 11.5 gallons 10.6 gallons
Price $9,199 $7,998 (144)/$8,499 (155) $7,849/$9,349/$10,199