1993 Ski-Doo MACH Z – Getting Back to the Muscle Sleds

“Lead, follow or get out of the way,”
is a motto often used in racing, but it also applies to the competition for your hard earned cash at the dealer showroom. Consumer demand (and the resulting profitability) is the driving force that manufacturers either create, or respond to quickly.
Twenty-five years have now passed since the 1993 Mach Z and its triple-piped 780 debuted and for Ski-Doo it signaled the beginning of their mission to regain its status as # 1 in worldwide snowmobile sales.

By Hal Armstrong

Ski-doo was at a crossroads as it entered the 90’s. The snowmobile market had shifted to independent front suspension and liquid cooling in the 80’s. Ski-Doo had reacted with a variety of models starting in 1985 based on their PRS (Progressive Reaction Suspension) front suspension. Ski-doo continued to refine this chassis for the trail performance category, but at the same time continued to investigate simpler IFS designs for the touring market. The cost of manufacturing two complete different chassis platforms as market share continued to drop was not helping Ski-doo. The market leader (Polaris) had settled on a single chassis for all the market segments and was making incremental improvements each year. Ski-Doo management knew that if they continued doing things the same way, the results would be the same – reduced market share. Change had to come from within!
The company brought in a new management team from outside of the snowmobile business to look at the “inside” of the company. What resulted was a shift in the way they designed their product. Change for the sake of change with no value added to the consumer was replaced by involving everyone at the plant, from design engineering to manufacturing.

Getting Back Into the Game

The rumors about when, not if, Ski-Doo would release a big bore triple to compete in the growing “Muscle Sled” category with the Polaris Indy 650, Arctic Cat 700 Wildcat and the new for 1992 Yamaha 750cc 4 cylinder VMAX-4 were running rampant. The rumors seemed plausible as a number of aftermarket companies were already building custom triples that were squeezed into the PRS chassis.
The previous Ski-Doo management team may have settled for milking the old chassis one more year fitted with a Rotax triple, but the team led by what many claim was the man behind the Ski-Doo turnaround, Tony Kalhok, had a plan in place developed three years earlier.
When the covers were pulled off in March 1992, two new models built around the new F-2000 chassis with DSA were revealed and yes there was a triple in one to boot! The Mach Z was the signature model of the new Ski-Doo. Kalhok had made it clear that Ski-Doo was aiming to move fast to regain its leadership role

F-2000 Chassis

The PRS system was the front ski suspension that Ski-Doo introduced back in 1985 on the Formula series of performance snowmobiles. Manufacturers were always trying to build a better mousetrap and Ski-Doo at the time was convinced their PRS system was superior. A patent was awarded to Ski-Doo engineering wizard Jean Guy Talbot and associate Andre Gauthier. Talbot wanted a front suspension that would absorb progressively more force without “bottoming out” and provide a progressive rate or rising rate suspension arrangement. In contrast the Polaris “Indy” used a linear rate suspension in which the spring would compress by a uniform amount for each inch of travel. Talbot was looking to provide a superior ride with a minimal increase in ride height. The design was simply to transfer vertical movement of the ski through a progressive rate lever arm to create a rising rate front suspension. The design, in conjunction with a tubular steel bulkhead, eliminated the belly pan of previous designs acting as a structural component. The tubular space frame used with PRS, while unique, added extra weight and complexity. The Formula series of sleds were great cornering machines and faired well in oval racing with numerous high profile victories. The design however had dimensional limitations, which restricted increased suspension travel needed to win in terrain racing. Ski-Doo needed to start winning on the Cross Country and Sno-X track. The company’s dominance of oval racing was less relevant than winning the I-500 or X-Games in the 90’s.
The result was the development of a new chassis platform labeled the F-2000 with a conventional trailing arm front suspension labeled “DSA” (Direct Shock Action). Yes, Ski-Doo had to swallow their pride with a chassis that closely resembled the Polaris Indy. The F-2000 chassis was Ski-Doo’s answer to reduce weight, increase travel and reduce manufacturing costs. Ski-Doo also invested heavily in manufacturing improvements now that the chassis was 100% aluminum.
The Valcourt plant was re-tooled for the new F-2000 chassis with robotics for welding and installing self-piercing rivets. Unlike conventional riveting, self-piercing technology does not require a predrilled hole. The rivet makes its own hole as it is being inserted. This technology is still used today in snowmobile assembly.
The F-2000 platform introduced on the Mach Z (and MX Z) would expand in just two short years to the majority of the 1995 lineup. It quickly would morph into the even lighter S-2000 platform in 1996 & 97 (originally destined for fan-cooled models), followed by the ill-fated CK3 (1998) and then the popular ZX (1999) platform until Ski-Doo hit the jackpot with their REV platform introduced in 2003.

Rotax builds a Triple-Triple

The Mach Z was powered by the infamous 780 Rotax triple. The engine in ‘93 had something new and old. The big surprise was the absence of rotary valve induction. The rotary valve which first appeared back in 1972 on the 400 Blizzard race sled was the reason Rotax was the undisputed HP king for a given engine size. The rotary valve system allows more fuel into the crankcase and prevents the fuel/air mixture from exiting out the intake tract. The down side was the added weight and complexity, which paved the way for the crankcase reed induction on the triples. The rotary valve engine would last be seen on a production Ski-Doo in model year 2000. The case reed valve engines found on the triples would be replaced by cylinder reed valve engines, a design still used today on the current 850 E-TEC engines we enjoy today.

Rotax engineers designed the 780 triple with case reed induction using three Mikuni flat slide TM38 carbs. The flat slide Mikuni carburetor provided significant performance improvements over the traditional VM round slide carburetor. Air flows faster and smoother through the TM Series. The high velocity of the air flow means a stronger vacuum at the needle jet providing more precise metering and better throttle response. All of the OEM’s have long used TM carbs for improved throttle response, most recently on their 600 SnoX race sleds.
Another unique feature was the use of the first-generation RAVE exhaust system. Variable exhaust, which is standard equipment today on all performance two stroke engines, combines the torque curve and fuel economy of a low port engine with the horsepower of a tall port engine for the best performance of both port heights in one package – along with reducing emissions while improving power, fuel range and economy.
It’s important to note that the majority of engines of the early 90’s did not have the sophisticated engine control module (ECM) used on all motors of today. Real time monitoring of engine exhaust and coolant temperature, throttle position, detonation monitoring were still years away. The 780 Rotax would have benefitted greatly from today’s ECM computing power, which could have varied the ignition timing to reduce exhaust gas temperatures to improve the engine durability.
Craig Marchback was a top drag racer for Ski-Doo in the 90’s and his knowledge of Rotax engines was second to none. Craig explained some of the issues with the first 780 triple. “I received my sleds in the summer of ‘92. There were three issues with the motor as it came from the factory that I had to deal with quickly and report back to Ski-Doo. These updates were later implemented in the updated 1994 version of the 780 triple.

1) Increased oil flow to the crank bearings was needed to prevent crankshaft bearing failure.

2) The cooling circuit on the 780 engines was allowing excess flow to the cylinder head and not adequately cooling the cylinders, resulting in pistons and crank bearings to fail prematurely. The solution was to tear the motor apart and open up the coolant passages in the crankcase to increase the coolant flow up the cylinders and over the exhaust ports while restricting flow to the cylinder head. This trick improved bearing and piston life and also contributed to a number of checkered flags for Craig that season.

3) A Comet 102C primary clutch came factory installed. For some reason the TRA clutch was shelved. Theories include harmonic and/or calibration issues with the TRA caused time to run out before production.

As it turned out the ‘93 Mach Z cylinders had larger exhaust and intake ports compared to the 94/95 versions. DynoTech reported close to 155 HP @8250 rpm, an incredibly high number even today for an engine under 800cc. According to Craig Marchback, the rotational harmonics of the 150+ HP of the 774cc triple made the Comet 102C primary clutch very unreliable, thus TRA clutches were quickly retrofitted to the 93’s.

It should be noted that Ski-Doo was not the only company that had issues with their triples that winter. Ski-Doo would treat their customers well as they replaced the entire engine, triple pipes and clutch with the ‘94 upgrade. Only the TMX flat slide carbs and air box were kept and the power jets on the TMX were plugged.

The race to be first across the lake

The ‘93 Mach Z was a limited build sled. Only 600 were built for North America. Ski-Doo shipped them with a fiberglass hood and tank cover.

The C7 rear suspension returned with Kayaba twin coil-over gas shocks on the rear progressive linkage arm and single coil-over gas shock on the front torque arm. Suspension travel was 7.5”. Wrapped around the C-7 was a 15” x 121” track. The C7 was no rMotion and while the ‘93 version of the C7 had lost some weight, it was a carryover design from the PRS sleds that Ski-doo was distancing itself from with their new chassis. The C7 would not be replaced until 1997 with the SC-10 rear suspension.
On the snow this sled’s performance did not disappoint. Only the ‘93 Thunder Cat with a 900cc triple upstaged the Mach Z. On the trail the DSA front suspension and C7 were good for the day. This was not a mogul mashing sled by any stretch of your imagination, these were tuck behind the windshield, pin it and hang on lake rockets! The Mach Z would make your eyes water. The scary part was bringing all that weight and speed to a stop as Ski-doo continued to use cable operated mechanical disc brakes. Brembo hydraulics would not appear until 1995.
How heavy was this sled compared to today? The ‘93 Mach Z weighed in at 530 pounds, compared to the 2018 MX-Z 850 (129”) that weighs in at 475 pounds. And we think sleds are heavy today? Triple-triples were heavy in comparison.

What Matters is What’s Next

This is the Ski-Doo slogan today and it is just as relevant as it was back in 1993. The new management team at Ski-Doo had set incremental goals for company, looking forward to the future.
The Mach Z and its sibling the MX Z on the new F-2000 chassis would usher in the company’s 2 millionth production sled and the first purpose-built mountain sled, the 1994 Summit. Ski-Doo had a chassis that it could now add all its future innovations on to build a line-up of snowmobiles that would bring customers back to their dealers. While the ‘93 Mach Z had some first year gremlins, the fact that Ski-Doo built a sled of this magnitude sent a message to the competition that Valcourt had woken up and were back in the game! It would take them ten years, but with the 2003 introduction of the rider-forward REV platform they finally would surge ahead and have never looked back.