4-stroke technology
When developing the engine for the new Phazer, Yamaha engineers called on two YZ250F powerplants. With a 499-cc displacement and a 43-mm dual throttle body, this 4-stroke twin-cylinder boasts a higher power-to-liter ratio than any 2-stroke engine in the entire industry. It uses a double overhead camshaft, 5 valves per cylinder as well as an impressive compression ratio of 12.4:1.


In order to achieve above-average maximum engine speed, Yamaha incorporated short-skirt forged pistons and ceramic-coated aluminum cylinders. Total output is rated at 80 horsepower at a stratospheric 11,250 rpm, one of the highest rev peaks in the industry. The Phazer also features a well-designed, push-button electronic reverse mechanism.

Snow-cooled muffler?
As for the cooling system, the Phazer is equipped with a heat exchanger located inside the track tunnel and a small radiator similar to the ones found on most ATVs. Cooling capacity can be improved by installing a thermostatic fan near the radiator; this easy-to-mount radiator (derived from the Phazer Mountain) uses a 12-volt outlet.

The exhaust manifold, made of stainless steel and titanium, passes underneath the fuel tank. Meanwhile, the muffler is mounted under the seat, although the exhaust tip emerges at the back like on the R1 motorcycle. This exhaust system makes the new Phazer uniquely styled and on the cutting edge of technology.


The exhaust manifold is cooled by the snow thrown from the track, as is the case with every other 4-stroke snowmobile from Yamaha. The only question is, why is the tunnel also open below the muffler? A number of ATVs and motorcycles use this type of exhaust system and they don't require a second cooling source in addition to air.