The new engine gained fuel injection and a much lighter crankshaft design. This 4-cylinder engine underwent its next evolution in 2006 for the Apex model. Eventually, the know-how gained in the development of this engine would form the base for subsequent development of the 3-cylinder and 2-cylinder snowmobile engines. Another factor in this was the specially designed crankshaft.įurthermore, the adoption of a rear-facing exhaust system made it possible to position the engine closer to the center of the chassis, improving space efficiency and making room for the first double wishbone type suspension ever on a Yamaha snowmobile.

These changes brought a reduction in engine height of approximately 30 mm compared to the YZF-R1 engine. Two of the solutions they came up with to make the engine lighter and more compact were an innovative layout for the three shafts (optimized assembly designs for each shaft assembly and positioning of the water pump) and adoption of a dry sump lubrication system. Looking back, the RX-1 development team members recall thinking of it as quite a large and heavy engine for a snowmobile. The original R1 engine had a reputation for high power output as a supersport engine, but the biggest challenge for the RX-1 development team was how to make the engine light and compact while retaining as much of the high power output as possible. In contrast, the crankcase, cylinder head, lubrication system (dry sump type adopted), cooling system, reduction (gear) shaft and other parts were redesigned specifically for the RX-1.

The engine of the RX-1 used the same pistons, connecting rods and intake/exhaust cam and valve systems as the YZF-R1 engine. Its base engine was none other than the epoch-making power unit of the original supersport motorcycle, the YZF-R1. The engine it employed was the 998cc liquid-cooled 4-stroke, DOHC, in-line 4-cylinder, 5-valve mill developed specifically for that project. The RX-1 launched in 2002 as Yamaha's first 4-stroke snowmobile was in fact, an offspring of Yamaha's fourth development project undertaken in 1999.

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