2009 Yamaha YZF-R1 - The Game Changer

Yamaha's Crossplane Crankshaft Changes Everything

By Aaron Frank, Photography by Paul Barshon

Yamaha's newest YZF-R1 sounds nothing like an inline-four. The syncopated growl instead suggests an extremely high-revving V-4. It doesn't feel like an inline-four, either. A bit throbby at idle, vibration actually decreases as you near redline. And it applies power to pavement better than any production four we've ridden, coming off corners with the steady thrust of a traction-controlled Superbike. Just like that, everything we thought we knew about literbikes has been turned upside-down.

Ever since Honda's archetypal CB750 appeared 40 years ago, every production inline-four has used a 180-degree crank. A pair of pistons arrives at the top of the stroke every 180 degrees, and combustion events occur precisely 180 degrees apart. Such predictability makes it easy to manipulate intake and exhaust harmonics for max power, but--especially on large-displacement bikes--the resulting crank speed fluctuations can compromise rear tire grip and feedback.

Crank speed is not constant with a conventional crankshaft. Starting and stopping each relatively heavy piston/connecting-rod assembly twice per crank revolution--at Top Dead Center and Bottom Dead Center--creates a pattern of micro-accelerations and decelerations that Yamaha calls inertia torque. This inertia torque travels like a micro-shockwave through the powertrain until it manifests as a shake or vibration at the rear contact patch, degrading grip and rideability.

Yamaha claims its Crossplane crankshaft technology--developed on Valentino Rossi's YZR-M1 MotoGP racer and making its production debut on the new R1--effectively eliminates inertia torque-induced "noise" at the rear tire. Crossplane crankpins are positioned 90 degrees apart, so a piston arrives at TDC/BDC every 90 degrees, compared to every 180 degrees with a conventional crank. As a result, two pistons maintain high speed as the other two are reversing direction, stabilizing crank speed. Reducing crank speed fluctuations reduces the power shake at the rear contact patch, resulting in smoother power delivery, improved traction and enhanced rideability.

The Crossplane crank is far from the only upgrade to the sixth-generation R1. The chassis has been completely revised to better exploit the improved traction and power delivery characteristics, the suspension has been modernized with more tricks from Rossi's racer, and the aerodynamic package has been retooled, too. It's a radically different machine, with more than enough changes to justify a 15-hour flight across the Atlantic for the official debut at Eastern Creek Raceway outside of Sydney, Australia.

From the saddle, the '09 R1 feels more compact and inviting than before. Reach to the bars has been shortened 10mm, and the saddle is relocated 7.6mm farther forward. Footpegs are now adjustable up and down as well as fore and aft. The new upper fairing seems more compact, too, an impression that was reinforced later while howling down Eastern Creek's 150-mph front straight. I noted a bit more buffeting when my helmet wasn't firmly mated to the tank.

The new R1 feels smaller and lighter, too, despite the fact that weight has climbed to a claimed 454 pounds wet, up from 436 last year. The magic of mass centralization effectively masks that extra 18 pounds. A stubby tail and shorty mufflers (now supported by a lightweight magnesium subframe) cut pounds far from the mass center, and the motor is angled 9 degrees upward and moved forward 8.2mm to allow the fuel tank to sit lower in the frame. These alterations, along with an optimized 52.4/47.6 percent fore/aft weight bias, help maintain responsive handling.

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