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November 2001: A tractor trailer rolled discreetly through the remote reaches of central Alaska. When the rig finally reached its desolate destination, a team of Yamaha technicians was there to greet it. Operating in total secrecy, few outside this select group knew the semi’s contents. Inside the truck sat a machine sure to shock the powersports world: the first high-performance four-stroke snowmobile.

In the final stages of testing, the sled, dubbed the OMX Project, was about to be unleashed upon an unsuspecting public. But Yamaha hadn’t rushed into the introduction. No, the manufacturer famous for cutting-edge products in all motorsports segments had spent decades preparing for the ultimate innovation.

Begin At The Beginning

Yamaha engineers knew a race-derived snowmobile was possible. After all, the factory has a long history of four-stroke success in the automotive, motorcycle, marine engines and now even personal watercraft sectors. They weren’t bound by any preconceived notions about the supposed failings of the four-stroke snowmobiles.

Yamaha has been experimenting with alternative engines in snowmobiles for many years. Most of these confidential projects were never seriously considered for production, but they spearheaded the R&D efforts leading to the creation of the world’s first full production high performance four-stroke snowmobile.

Yamaha began testing four-cycle sleds about 20 years ago. The first prototype was based on the extremely successful Enticer chassis using a GX 400cc Yamaha motorcycle engine.

By the start of the 1990s, Yamaha was putting the final touches on the soon-to-be-released Vmax-4. While all the attention was on the revolutionary four-cylinder, another project sled was quietly ripping up the test track at Yamaha’s Minnesota R&D facility. A seemingly stock snowmobile with a very distinctive exhaust note was writing the second chapter in Yamaha four-stroke snowmobile history.

The secret sled was powered by an FZR 400 motorcycle engine that produced a wailing 60hp at close to 14,000 rpm. The power sensation was actually quite good. It pulled hard, closely matching the performance of the Phazer fan-cooled two-stroke. Of course, there were obstacles. High rpm power delivery, air management, cold starting, chassis balance and weight were some of the factors that needed to be dealt with at the engineering level, but the prototype gave strong indications of good snowmobile four-stroke potential. Immediately evident were the inherent power characteristics of the four-stroke engine. Four-stroke torque—especially on the low end—far exceeded typical two-strokes. The extra torque dramatically affected the weight transfer, traction and overall pull of these early test sleds. At the time, it seemed the additional torque would be most appropriate in a workhorse machine, like the legendary VK wide track. The torque discovery led Yamaha to develop another project sled using motorcycle technology applied to a more utility-based platform. A larger displacement 850cc liquid-cooled engine, TDM twin-cylinder engine proved to be a worthy candidate for the application and underwent several stages of prototyping in the mid 1990s.

However, Yamaha desired to create something so new, so advanced, so groundbreaking, that the entire performance world would stand up and take notice. Looking for parallels, engineers studied previous products. The factory had a concept for a machine that could satisfy key snowmobile requirements: the need for speed and tremendous torque. The choice quickly became obvious: a high performance Yamaha motorcycle would provide the four-stroke sled foundation.

A New Millennium

Yamaha’s latest engine technology had just been introduced in a new motorcycle and was an instant homerun. The awesome R1 set a lofty benchmark for a new breed of sport bikes. The horsepower-to-weight output of the patented 20-valve, four-stroke four-cylinder engine was nothing short of a full-blown factory superbike. Hours of testing, racing and endurance in the market had proven this new, lightweight engine was extremely reliable.

Yamaha knew that the low-end torque of the R1 motor was almost double that of a typical two-stroke engine and produced similar peak horsepower. Would it offer the hit to satisfy the most demanding snowmobiler? Could Yamaha harness the power and package it in a chassis that would put it on the snow? There was only one way to find out.

The Concept

After project approval, the RX-1’s early days followed the usual pattern: customer research and internal discussion. Yamaha first identified engineering and marketing targets. The perception of four-stroke engine snowmobiles included some unfound negatives. People believed them to be bulky and heavier than a comparable two-stroke, less powerful and more difficult to handle. However, those same people also thought four-strokes would have superior fuel economy, run quietly and reliably and would be the eventual future of snowmobiling. They were right about the latter, but the future came sooner than they dreamed, and in a package that would blow away their unfounded negative notions.

Yamaha had to build a machine that went beyond all expectations. The visual impression had to have strong impact. Sleek, functional styling would need to shrink wrap the chassis to help dispel the weighty image. The heart of the best could leave no doubt that four-stroke power would deliver all the fun and excitement demanded by the most experienced riders. The styling people said, “no problem.”

Styling and engineering models were produced, tweaked and refined. Ergonomic and aerodynamic testing was done while chassis and suspension components were developed. To achieve engineering goals, the chassis for the OMX Project had to offer the lightest weight possible with more rigidity than any Yamaha production snowmobile ever produced. The overall target: A great handling, superior performance chassis that would maximize the benefits of a high torque, four-stroke engine. Consider the RX-1 a bull’s eye.

To make this goal a reality, the balance of the sled needed to have its mass and weight centered and carried as low as possible. It wouldn’t make any sense to have the cylinder block angled forward, over the ski spindles, or perched any higher than needed. The moment of inertia was quickened and the center of gravity lowered by rotating the engine 180 degrees and canting the cylinders 30 degrees rearward. This effectively moved the engine mass towards the driver, allowing the sled to respond more quickly and accurately to steering inputs. Predictability, stability and control were enhanced, resulting in outstanding rider confidence.

Early testing was performed on a modified R&D prototype using an all-new unequal length double wishbone front suspension. Weight was added to different areas of the chassis to affect balance. Not surprisingly, handling deteriorated when weight was added to the front. However, handling improved with the weight moved to the very rear of the tunnel. This led to an exhaust system layout locating the muffler in the rear end of the tunnel and taking weight normally supported by the skis and repositioning it over the rear axle.

A new aluminum-alloy, high pressure, high vacuum die-casting process was developed to offer several key chassis components exceptional strength while further reducing weight. The main bulkhead and bulkhead sub-frame were both die-cast and tied together with a high-strength extruded aluminum tube to create the all-new Deltabox chassis.

The extreme rigidity provided by the Deltabox design was key for the application of the dual wishbone front suspension. The front suspension had the ability to produce superior handling characteristics, because the chassis resists flex and does not spring from torsional loading of the front end.

There was every indication that this unique suspension system would eliminate bump-steer and deliver superior bump compliance with less under-steer, or push—all key points to give the rider unsurpassed comfort, confidence and control. The rolling chassis was ready for testing.

Fantastic Four

The R1 engine makes awesome horsepower and torque but does so using high, peak rpm. That’s not a problem for motorcycles using standard transmissions, but in the case of variable V-belt transmissions, rpm and durability have a fine line of balance. Motorcycles also seldom see use in sub-zero temperatures and therefore require little consideration for cold temperature starting. It was obvious that a lot of re-designing was needed to produce an engine of R1 capability for snowmobile use. And so the R1 powerplant underwent a complete makeover.

First, a secondary output shaft would deliver power through a pulse-isolated geared reduction drive, spinning the modified YXRC primary clutch at a reliable 8550 rpm (down from a crank speed of 10,200). A dry sump oil lubrication system was developed using a high volume oil pump with a remote oil reservoir.

A heavy-duty, 425-watt rare earth flywheel magnet would handle the charging duties, and an all-new high output starter motor would supply the cranking power for reliable, sub-zero starts. The engine would receive its ignition spark from another industry first: top coil plugs incorporating highly efficient coils right in the plug caps. Fueling duties were assigned to a bank of liquid-heated 37mm constant velocity carbs.

Many hours of bench testing and cold room operation resulted in extremely positive performance and reliability data. Another four-stroke myth was exploded: cold-weather starts would be quick and easy.

Here And Now

The body, chassis and engine came together in prototype form during the fall of 2000. The first RX-1 was crated and shipped to the Yamaha winter testing facility located on Hokkaido, Japan’s northern-most island. With great anticipation, Yamaha’s development team members from around the globe assembled in the small town of Shibetsu to determine the performance potential of the new sled.

However, with minimal clutching and suspension setting time, the expectations of the group were conservative. It took less than three seconds to dispel all doubts. The prototype lined up beside a strong-running SRX and literally drove away from it. The RX-1 had liftoff.

Fast forward to November 2001. Based on years of testing, refining and improvements, final prototypes were assembled and shipped to Alaska. These prototypes were hammered relentlessly on the unforgiving tundra. Mile after mile was turned, and further adjustments were made. Testing then moved to the trails of Wisconsin and Michigan, and to the mountains of Montana. Every target was hit. Hard.

Throughout the rigorous development process, one thing remained crystal clear: This project was an incredible achievement. The Yamaha RX-1 is set to change the future of snowmobiling.

1,736 Posts
Looks like a very well written marketing article.  They made it sound like there isn't anything that this machine can't do.  A bit too much padding, IMO.

138 Posts
Same I said the first time I seen it Wolfman. Yamaha did a great job writing that.

1,042 Posts
Now if Yamy waould get off their backends and build a 440 class racer that can compete with the others. As well as competitive small bore machines in the 500 and 600 cc class so people that can not afford to insure the bigger machines could have a competitive machine they can aford to insure.

There is way to much being put into these large bore machines lately with not much being put into the top selling classes of sleds such as the 500cc and 600cc.

I am not saying Yamaha is an inferior manufacturer I am saying that they are letting these smaller classes slid because they do not feel they are good sellers. The only reason yamahas smaller sleds did not sell as well was because they were a bit under powered compaired to the other manufacturers entries in these classes so they did not sell as well.  In the thousands of miles I have logged in on the trails I see far more 500s and 600s on the trails than I do the 700s and higher.
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