Snow Technology 2002

Technology and Trends of the new 2002 Models

Power Valves: Finally, for the model year 2002, we have power valve engines from all four manufacturers in all segments of vehicles. New for the 2002 model year are power valve engines from Yamaha (single pipe 700 triple in the SXViper) and Polaris (single pipe 700 & 800 twins).

The power output characteristics of a two-stroke motor are in part determined by the height of the exhaust port. A low port height provides an engine with good low-end output, while a high port height provides better peak horsepower. Generally, engine designers had to settle for a port height somewhere in-between that provided both acceptable low end performance, but also acceptable peak horsepower. The addition of an exhaust port modifier provides the characteristics of both designs; good low end power with good peak output. If you were to overlay the power curve of a low port and high port design, then find the “cross-over” RPM where the power curves meet, this is right about the RPM at which the valves are opened and closed.

With most of the emphasis being placed on horsepower, non-valved snowmobile engines have traditionally been designed more on the high port end of the spectrum. The addition of valves typically provides slight increases in peak output, and typically greater increases in low-end output. Since the motor is operating at a lower port height more than it ever did before, additional benefits include a reduction in exhaust noise and an increase in fuel economy. Note however that these benefits are only realized when the engine is operating in the low port mode. Continuous high port operation will still be as loud and use as much gas as before, all other things being equal.

Technically, the term “power valves” more accurately describes the Yamaha version of exhaust port modifiers. Only Yamaha readily uses the full term “power valve” for their electronically servo-motor activated system. Polaris calls their mechanical pressure-activated exhaust port modifiers “VES”, or Variable Exhaust System. Arctic Cat uses two different descriptions, “APV” for Arctic Power Valve, or “VEV” for Variable Exhaust Valve for their servo-motor electrical system, similar to Yamaha. Ski-Doo calls their system, the simplest (pressure-activated) of all, “RAVE” for Rotax Adjustable Variable Exhaust.

Ski-Doo (Rotax) introduced the first exhaust port modifiers on snowmobiles back in the mid 80’s on their race sleds. It wasn’t until 1988 that the first consumer production sled, the 1989 Mach 1 583, featured RAVE valves.

The electronic systems used by Yamaha and Arctic Cat are the most accurate, opening and closing the valves at specific RPM levels. Their systems both incorporate auto-cleaning cycles at start-up, supposedly helping to reduce carbon build-up that can cause the valves to gum up and stick, reducing ease of valve movement. While the pressure-activated valve designs used by Ski-Doo and Polaris are simpler and far less expensive to manufacture, they also are more susceptible to changes in operation due to carbon or gumming of the valve. Both of these systems are spring-loaded, so when the valve becomes more difficult to move, the “pop-off” RPM can change which can affect performance.

Wider Running Boards: What started as a usage-specific feature for the stand-up riding style of mountain riding and snow cross racing (and some two passenger models) has found greater acceptance across the rest of the Ski-Doo and Arctic Cat model lines for 2002. The introduction and integration of new tunnel designs has helped this manufacturing change, as wider running boards are on many of the 2002 MX Z and ZR models. It shouldn’t take a rocket scientist to realize the benefits afforded by having the width of the running board extend further towards the rear of the sled, especially if any of your riding may require your feet to be located somewhere other than locked up into the footrests.

Higher Handlebars With Hooks: Very similar to the explosion of wider running boards, more sleds for 2002 feature race-style handlebars; higher (or easier adjustable) with integrated hooks. At first, one may think this is simply eye-candy trying to attract buyers, but the function is undeniable. Riders come in all different heights and arm lengths, and the ability to set the handlebars to better match the rider size and riding position allows greater control and comfort of the sled. Again, for riding styles that may include some stand-up riding, this is a long over-due and welcome trend, as evidenced by the popularity of rider blocks this past season.

Four-Stroke Engines: We can likely credit the National Park Service for this development more than anything; if it hadn’t been for the threatened closure of Yellowstone National Park, we’d likely not be seeing four-stroke powered snowmobiles being offered for sale by Arctic Cat and Polaris. Even without the YNP fiasco, there is mounting data that suggests there would be enough buyers to support such vehicles. Issues like noise, smoke, fuel economy, reliability, and the type of power delivery are actually attractive to many potential snowmobile owners, even a number of people who currently don’t ride or own sleds. The industry has been looking for a way to lure more people to the sport; they may have just found it. Will Ski-Doo and Yamaha follow suit? If they do, it likely won’t be down the rental path. More likely is Orbital-based clean two-stroke technology from Ski-Doo that has proven its performance and reliability in their Sea-Doo applications. As for Yamaha, need we say anything more than YZ 426 or Raptor? These vehicles are about as far as you can get from “entry-level”.

1.25” Lug Height Tracks: Seeing a 1.25” track on production sleds is rather surprising; not because the demand isn’t there, but in the past it’s been like the manufacturers had un-unwritten rule that none of them would exceed 1” track lug heights in order to please groomed trail administrators. The generally accepted wisdom has been that deeper lug tracks do more damage to trails, and that by restricting (or at least not installing them at the factory level) deeper lug tracks on 121” machines that the trail quality would be better. This may be true to a point, but we firmly believe that the greater destruction to groomed trails is caused by track spin; regardless of lug height. OK, spinning a deeper lug track may do more damage than spinning a shallow lug track, but the real culprit here is the behavior, not the product. (“Guns don’t kill people, people kill people” mentality.)

1.25” tracks in production machines has in the past been limited to race vehicles and select limited build models. Now for 2002, Polaris is offering, as an option, 1.25” lug height tracks on their Spring-only XC orders. Not quite full production numbers, but there will be even more of them out there. Ask any dealer; they’ve likely installed more 1.25” tracks this year than any other. While many are OEM versions, our favorites have been the Camoplast Predator versions, both the traditional lug pattern and the round conical “New” Predator.

Heated Carbs: Every manufacturer likes to point out all of the technological advancements they brought to market first, but sometimes it is perfectly OK to be the second one to offer a good feature with true benefits. Case in point, heated carbs. In this case, Yamaha was the first, but they needed to be because they suffered more air-jet freezing than the other brands. Ski-Doo has now added heated carbs to many of their Summit and Series 3 engines in many 121” models to provide consistent performance in adverse conditions. It is usually a very condition specific problem, based on air temperature, relative humidity, and the type of snow dust flying around in the air, but there are times that adding isopropyl isn’t enough to keep the carbs free due to the venturi affect of increasing air speed through the carb, and the formation of ice in the passages. The result is a rich fuel mixture, poor throttle response and fouled spark plugs. By routing coolant through the carb body, this icing of the air-circuits is reduced and pretty much eliminated.

Sliding Hood Closures: This one Ski-Doo started back 1994 on many of their F-2000 chassis sleds, and now Polaris has added a similar feature to many of their 2002 models. Whether it be the desire to block off or reduce the flow of super cold air when riding in sub-zero temps, or reducing the entry of powder snow into the under hood compartment, the ability to open or close vents when and where you want to is a nice feature.

Longer and Longer Mountain Sled Tracks: It almost makes one wonder if the manufacturers were in collaboration on this one. The 136” tracks had been the standard mountain sled length since the mid-nineties with the introduction of the first mountain-specific Summits. Up to that point, the 133.5” Polaris SKS models were the standard. Then all of a sudden in 2000, Yamaha thought they had the market cornered with their stretching of the Mountain Max to 141”. Not to be, Ski-Doo quickly responded with a 151” Summit Highmark. 2001 brought us 151” models from Polaris and 144” Mountain Cats. 2002 brings us 151” Mountain Cats, and now for the first time ever, a 156” production mountain sled in the 2002 Polaris 800 RMK Vertical EDGE 156”. A Snow Check only model, those who live for the deepest powder they can find are sure to step up to the plate and get a sled already equipped with what has been an aftermarket-only option.

Position Sensitive Shock Damping: Polaris has it, and openly calls it position sensitive damping, while Arctic Cat has it but gives it a totally different name. How many Polaris riders aren’t going to realize that Arctic Cat has something similar and potentially better simply due to the lack of descriptive terminology? Arctic Cat refers to their version as “SS”, or Smart-ride, but call it what you want; it is definitely an electronic PPS. Ski-Doo also has their own version of position sensitive shocks with their “Variable Rate” or VR shocks, a triple tube shock design with mid-stoke bypass valving. This new design is being offered on the GS option packages of Legend and Grand Touring models. Expect this trend to continue, from more models to more manufacturers. Maybe Polaris just also happens to have a smart version of their design that’s being readied for future models.

Spring-Only Options: Many years ago, the manufactures all had a good thing going with their spring programs. Polaris really had it nailed, but the strong Spring sales slowly eroded as buyers figured out that over-production made it possible to get the same sled in the Fall for an even better price. Why buy early if this was the case? Now the manufacturers have gotten savvy; offer special models that can only be ordered in the spring. Keyword here being “only”. Yamaha plays this game the least, with no Spring-specific models, just incentive packages. Ski-Doo, Polaris and Arctic Cat have Spring-only models loaded with features. The benefits to the manufacturers are clear; let’s make sure the benefits to the consumer remain clear also.

Push-Button Electronic Reverse: Many of us realized years ago that a two-stroke engine could run backwards. Trying to start old sleds would occasionally result in a backfire, then as you pressed the throttle you realized the engine was running in reverse. Some clever Rotax engineers figured out a way to intentionally make this happen, and control it. The engine RPM is slowed way down, and the ignition timing changed so the engine actually fires in a reverse rotation. Ski-Doo even patented the process. The Rotax Electronic Reverse (RER) was first featured on the 1998 Tundra R and Touring SLE models, small fan cooled models that provided valuable field experience.
Now in 2002, Ski-Doo has made this feature available on many of their liquid cooled twins, including MX Z and Summit models. Yet even more surprising is the fact that Polaris offers a similar feature (“under license” from Bombardier) on their 2002 model 600 Classic Touring. The details of this agreement are less important than the fact that Polaris also recognized the benefits of such a system; simplicity and lightweight.

Detonation Sensors: The 2002 SRX may be the only sled right here and now to offer a detonation sensor-based ignition, but this one is so significant that it is very likely to show up on more models in the very near future. With all of the sensor-based ignition systems, it was only logical for a detonation sensor to be added to the list of sensors supplying data to the ignition system to base the ignition timing on. Now, if the sensor detects the damaging “shock wave” of detonation, the ignition system can roll back to avoid costly engine damage. The benefits are huge; reduced down-time and warranty costs, crisper jetting possible without the fear of damage, reduced emissions from leaner jetting, no more having to swap jets all the time because of environmental changes, and the peace-of-mind that you’ll likely never squeak a piston again due to poor fuel or lean jetting. This feature should be standard issue on every single high performance snowmobile built, period. We suspect it will be standard issue on more sleds very soon.

Two-Way Coupling: Credit Gerard Karpik and the FAST M-10 for what has finally become standard issue from all manufacturers. Polaris was the first to recognize the benefits of two-way coupling, from “communication” of the front and rear arms, to “angle of incidence” rail-angle control and resulting pitch control, to all of the ride quality and handling improvements afforded by the limiting of the rear arm and combining spring rate and shock damping of the front and rear arms.

The FAST M-10 eliminated the traditional lower half of the rear arm “scissors” and replaced it with a sliding “slot” at the pivot point. This system works the same, regardless of the rail angle for a more consistent moment of coupling. Polaris emulated this affect by placing blocks in front of and behind the rear arm, with similar results. Yamaha opted for another set of control rods, controlling the “gap” to arrive at their desired result. Ski-Doo placed the block on the rear arm and used rubber bump-stops instead. And now in 2002, Arctic Cat has finally added a block behind their rear arm to complement the cross-shaft in front of the arm for full two-way coupling. The result? Better weight transfer control, flatter cornering, less pitching in the bumps, and an increasing rate of bottoming resistance.