Här är några fakta: "The last item that really impresses me is that not only has Yamaha pumped 18 additional horsepower into the new Viper engine, it used 1/2 the oil and gets 15% better fuel consumption."
"The engine is based on the legendary SRX motor, but it's 696cc triple powerplant is new from the case up. The engine shares some of the similar design attributes of the SRX. The triple exhaust ports are smaller versions of the SRXs, but the cylinder castings are more compact than the SRX making the cylinders lighter. The Vipers exhaust ports are also CNC machined which helps provide more consistent power curves.
Along with the cylinder castings being lighter in weight, the one-piece head on the Viper reduces weight even further. The Viper is also the first Yamaha to offer varied compression ratios by cylinder. The #1 cylinder ration is 5.9:1 while the #2 and #3 cylinders ratio is 6.7:1. You'll use the same main jet sizes on all the cylinders as you add pipes or silencers to the Viper. The issues of staged jetting are completely eliminated. Almost as good as fuel injection.
The weight savings continue within the engine with the crank shaft. The Yamaha tradition of using heavy duty duplex rollers continues as well as crankshaft welding to provide extra strength. The new design remove material from the crankshaft where it's not needed to reduce rotational weight by 1.5 pounds."
"The improvement that you'll notice the second you fire up your Viper, is the new ignition system. The 18-pole stator design delivers a whopping 300W of power for the brightest whitest light on the market. The 360° D.C. ignition system also fires each plug separately for strong and consistent spark. To continue still with Yamaha's weight saving measures, rare earth flywheel magnets are used like in the SRX. Rotating mass is reduced by 2 pounds. The end result of the new system is a better timing curve that increases low-end power and throttle response. The lights also never dim when the snowmobile is idling."
"The reoccurring theme continues to be weight savings. Numerous changes to the frame, bulkhead, cooling system heat exchangers and the generous use of aluminum have taken another 4 pounds off the chassis. The engine is set lower in the chassis than last years SX 700 lowering the center of gravity and improving cornering characteristics. Small details that helped remove weight are the aluminum rear bumper design and the bracing in the engine compartment."
"The strongest chassis in the industry features increased aluminum usage to reduce our already-industry-lightest chassis weight. New parts include a lighter frame and tunnel design, aluminum front bumper brackets and aluminum rear bumper."
"Best New Motor: There really aren’t all that many new engines this year, and we don’t expect too many in the next few years as we all wait for the EPA to (some year) get around to telling us exactly what our future emissions targets are going to be. This award has to go to the newest triple in the Yamaha SX Viper; yes, a triple, in a world of twins. When we get into this kind of power output, the advantages of a triple become obvious, despite a generally heavier engine. The smoothness, broad power band, fuel economy, technologically advanced ignition system, and the lowest engine noise levels yet from a high performance two-stroke snowmobile engine. The new Polaris VES 700 twin deserves honorable mention, and this engine will likely outsell the Viper. The VES 800 is still too rough around the edges to be seriously considered. The 570 fan-cooled Suzuki (Arctic Cat) is nice work, but it’s pretty basic. Least impressive new motors? The 800 EFI from Cat was not ready (yet), nor was the 800 VES twin from Polaris"
