50th-finalAs Snow Goer celebrates the 50th anniversary of its founding, it has given editors a chance to page through each and every edition of the snowmobile magazine’s stories past. Occasionally this season, we’ll share articles that, for one reason or another, caught our eye during that research. The review of the 1985 Ski-Doo Formula MX snowmobile was published in the November 1984 issue of Snow Goer, with opinions based on the magazine’s tests of pre-production models the previous spring and a lot of background of what went into building the snowmobile.

Also a part of the Snow Goer 50th Anniversary celebration is the Get Up & Go Sweepstakes. Make sure to enter to earn a chance to win a 2017 Ski-Doo Renegade Adrenaline 850 E-TEC snowmobile, a two-place Triton trailer, power tools from Makita, a helmet from BRP, Dennis Kirk gift certificates and other great prizes. Click here for details.





Ski-Doo’s Formula MX

The Wait Is Over… Ski-Doo’s Got The Beef!

By Bill Monn

This is the lead image from the November 1984 issue of Snow Goer magazine, reviewing the 1985 Ski-Doo Formula MX.

When the trail wars kick-off this winter, no one will have to ask Ski-Doo “Where’s the beef?”

The “beef” from Ski-Doo this season comes in the form of the new Formula series.

Ever since the snowmobile manufacturers began offering high performance IFS trail stampers in the early 1980s, the recurring question we’ve heard was when was Ski-Doo going to get something together. For the 1985 season, those prayers (or laments) will be answered – resoundingly.

Granted, the Formula Plus, with its awesome 521-liquid, will be the flagship of the performance group. But it will be the Formula MX that will be showing up in the greatest numbers in trail wars. It is the MX that will go up against the redoubtable Indy 400 and the brutish SRV; the Cat-quick Cougar and the Star­Wars Phazer. It is the MX that will most often carry the Ski-Doo colors into competition. And, in the final analysis, it is the MX that will make or break the reputation of the entire Formula line.

That’s a pretty heavy-duty responsibility for a sled in its very first year of mass production. Yet, if any sled Ski-Doo ever has produced is up to the challenge, the Formula MX is it.

In the MX’s arsenal is a 463cc, liquid­cooled, rotary-valve Rotax. Fueling the MX is a pair of Mikuni 34mm carburetors. Breathing is enhanced via a tuned pipe and after muffler.

This is the engine racing ace Gerard Karpik likes to describe as “a good trac­tor motor.” The translation of that statement is that the 463 has a ton of low-end and midrange torque. And when you stop and think about it, that’s the essence of a great performing trail sled. All-out speed is nice, but you make your time going into and coming out of the corners. The motor that can pull the competition at 20, 30 and 40 MPH is going to be the one that is out front. Just ask Karpik. He’s been in a few ski-to-ski, coming-out-of-the-corner acceleration contests.

But, getting back to why Ski-Doo is five years behind in getting a high performance IFS trail model off the assembly line. Well, that’s going to take some explaining. To fully appreciate the Ski­Doo Formula, we have to go back nearly 10 years.

This cutaway gives you a better idea of the sophistication built into the Formula MX. (Original caption from November 1984 issue of Snow Goer magazine)

Performance independent front suspensions hit with a flurry on the oval racing circuit at the beginning of the 1976-77 season when Polaris introduced its RX-L model: It was a fantastic success. The other manufacturers soon had IFS projects in the works. Soon, the open question became: “When will the new suspensions find their way into the consumer lines?”

Arctic Cat was first to answer the call with its 1979 model Trail Cat. But this was not a “performance IFS.” Rather, the Trail Cat was designed and marketed as a family trail sled with an advanced front suspension – “The Mogul Magician,” as the Arctic ads put it.

The first true performance IFS came from Polaris the following year in the form of the 1980 model Indy. Polaris made no bones about it. The Indy was built to win the Winnipeg-to-St. Paul I-500 race. Fast on the Indy’s flap was Yamaha’s Telescoping Strut SR-V. This too was built primarily for performance. Finally, the following season, Ski-Doo came out with its Blizzard 5500 MX.

The problem with the Ski-Doo Blizzard MX is that it never was spelled out just what this sled was supposed to be or, more importantly, just what it was supposed to do. Expectations from consumers were that the MX would be in the Indy and SR-V category of performance. Ski-Doo didn’t do anything to temper that expectation when it gave the sled to Karpik and told him to race it in cross country wars. Well, the Blizzard MX simply was too heavy and too bulky to be anywhere near competitive.

But let’s not write this sled off completely. What the Blizzard MX did offer was a superior ride – front and rear. Over washboard moguls, this Blizzard may have been the best combination ever offered to consumers. Period. If Ski-Doo would have marketed this sled by telling consumers that it was primarily a long-distance touring machine with superior suspensions, the Blizzard MX perhaps would have had a much more successful life.

Snowmobile buyers, however, expected and wanted an Indy-beater. Soon there were gripes: “The Blizzard MX is too heavy,” or “It’s under­powered,” or, “It doesn’t corner.”

Going into the winter of 1981-82, Karpik & Co., lobbied for and was granted the authority to develop a PERFORMANCE IFS. This time the goal was clear: produce a sled to go head-to-head with the lndys.

The rest, as they say, is history.

Karpik hand-built a couple of racers and showed up at the Alexandria snocross in December of 1981. Karpik drove one and Brad Hulings drove the other. Running with the leaders, Karpik’s machine broke a two-bit part and went down. Hulings’ sled ran flawlessly and went on to take the checkered. Later that winter, running with the 521 motor, Karpik and Brian Musselman won the prestigious Soo 1-500.

Consumers clamored for this new IFS-racer, dubbed the KS (Karpik Special) by SNOW WEEK magazine. But, to Ski-Doo’s credit, there simply were too many hand-built parts on the sled – parts that didn’t fit nicely into assembly line techniques – and it was decided that development would continue for at least another season.

The Formula MX rear suspension features three, progressive-rate, coil-over shocks. (Original caption from November 1984 issue of Snow Goer magazine)

In the winter of 1982-83, the second generation Performance IFS was pieced together. This time, the sled was more of a mix of what worked best on the assembly line and what worked best in the interests of performance. It was sort of a watershed year in which the race shop and the consumer sled development groups at Ski-Doo tried to find some middle ground. That sled could not duplicate the fantastic results of the inaugural year. Nagging problems seemed to continually plague it.

Karpik explains that most of the problems were in the rear suspension. He said they were off on the shocks early and, instead of stepping back and concentrating on the problem, continued to race each week. “That was a mistake,” Karpik admits. “We should have fixed the problem right away. Instead, we kept racing each week and never did quite get it ironed out.”

Last winter a pilot run of 50 Performance IFS sleds were sold to independents. Karpik semi-retired and concentrated on R&D. He left racing to younger bodies. And, finally, the third generation IFS performance model got a name: The Formula MX.

Working with the Bombardier Can-Am motorcycle experts, Karpik & Co. developed a sophisticated rear suspension that incorporates three coil-over-shocks – one fore and two aft. The rear offers six and a half inches of travel, which matches the travel up front. Both are rising rate, progressive designs, which sim-ply means they provide greater resis­tance as more demand is put on them.

Balancing and matching the front suspension with the rear should not be underestimated, Karpik points out. If the front suspension has marvelous travel but the rear doesn’t, the sled doesn’t work well as a package.

In concept and design, the Ski-Doo IFS bears most resemblance to the Indy IFS. Both have dual radius rods, of sorts, while the new Arctic features an A­Frame and Yamaha has its telescopic strut. Differing from the Indy, the Formula’s front suspension is positioned inboard. By keeping the coil-shocks under the hood, fewer parts are exposed to be damaged and the suspension parts also don’t interfere with the snow-planing characteristics of the bellypan.

On the snow, the Formula MX offers a very “tight” feel. The front sucks up bumps and keeps the skis on the snow. There’s no wishy-washy feel. The rear suspension responds quickly and methodically. Although a bit stiffer on the initial bump than either the Indy or the SRV, the Formula seems more poised to handle the second, and third and fourth bumps – it seems to return to “ready stage” quicker.ski-doo-formula-mx-specs

It also should be noted that, with three shocks in the rear, the Formula’s suspension can be more finely tuned, but it also requires more adjustment time than other models. It seems that you can’t just jump on this one and expect the suspension to work exactly to your liking. Instead, Ski-Doo seems to be telling consumers to fine-tune this one according to individual preferences. It will take a little more work but the end result seems to us to be worth it. You can dial it all the way to heavy-duty if you are going to race or all the way to soft for moderate trail riding. The Formula MX is a thoroughbred IFS trail stomper that has been defined and refined in three grueling seasons of snocross, enduro and oval sprint racing. It now is ready, willing and quite capable of meeting every expectation of the high performance trail rider.

Believe us, absolutely no one is going to ask you: “Where’s the beef?”

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