2004 Yamaha YZF-R1 Engine Details 1

• Completely redesigned short-stroke 998cc, DOHC, 20-valve, liquid-cooled, inline 4-cylinder engine now produces 180 horsepower at an amazing 12,500 rpm (with Ram-Air).
• All-new, 27mm narrower fuel injection system uses motor-driven secondary throttle valves and 32-bit ECU for super-responsive, instantaneous power delivery.
• Two-piece ergonomically designed fuel tank carries fuel in the rear section, for good centralization of mass, while the front half contains a new, Ram-Air-fed airbox for increased power.
• Re-angled cylinder head-40 degrees forward instead of 30-optimizes weight distribution, straightens intake tracts for improved cylinder filling, and allows frame to pass over instead of around the engine for great strength.
• Radical new closed-deck cylinder block reduces cylinder pitch, allowing an engine with 3mm wider bores to grow only 2.8mm wider instead of 12mm.
• Narrower-angle 5-valve combustion chambers produce a highly efficient 12.3:1 compression ratio. Bigger valves and intake cams with more lift and duration flow more air.
• 16% lighter crankshaft, 3% lighter forged pistons, and 9% lighter 7.5mm shorter carburized connecting rods with perfectly mated big ends add up to a quicker-revving engine with excellent high-rpm durability.
• High silicon-content ceramic-composite cylinder sleeves ensure greater heat dissipation for consistent power delivery and reduced friction.
• Strong, yet lightweight clutch and close-ratio 6-speed gearbox with triangulated shaft layout for increased strength, compactness, and quicker acceleration.
• Titanium underseat exhaust system (except for stainless steel midpipe with catalyst) contains a new titanium EXUP valve for a broad, seamless powerband.
• High-efficiency curved radiator and an aluminum liquid-cooled oil cooler maintain stable operating temperature.
• Direct ignition coils, new dual-electrode spark plugs and high-output magneto deliver more reliable firing.
• AC generator moves behind cylinder block for a narrow engine with excellent cornering clearance.

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