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Refined Specimen
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2007 Yamaha YFZ-R1
Jeff Buchanan
01/03/2008
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Action photos by Don Williams
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In the vehemently contested liter-machine wars, manufacturers are allowing more technology to trickle down from their GP racing endeavors to their production line-ups in order to gain an edge over the increasingly fierce competition. In Yamaha's case, some of the advances trickling down are coming from legendary 7-time World Champion Valentino Rossi. Intent on creating the omnipotent 1000cc sportbike, Yamaha brings to bear a host of MotoGP-inspired advances to the fifth generation YZF-R1. And it's not all just marketing fodder for the brochure.
Since its introduction in 1998, the R1 has enjoyed an aggressively robust reputation in both aesthetics and performance. For 2007 Yamaha builds on this persona, refining it into an even more impressive package. Extensive wind tunnel testing renders the most slippery aerodynamics to date—right down to the screwless windscreen for minimum drag—allowing the R1 to effortlessly slice the atmosphere. The new bodywork is constructed of layered cowlings designed to draw heat away from the short-stroke 998cc DOHC, 16-valve, liquid-cooled, in-line four cylinder engine. The gas tank (4.75 gallon capacity) is a two-piece affair with fuel carried in the rear section for mass centralization of weight and the front half containing the airbox, which is fed by large Ram Air intakes to aid breathing.
The most significant rollover from Yamaha's GP garage is the R1's fly-by-wire throttle system.  Officially trademarked YCCT (Yamaha Chip Controlled Throttle), it translates into the fact that twisting the throttle is no longer a mechanical operation. Instead, throttle input passes through a 32-bit ECU (Electronic Control Unit) fuel injection system that ultimately feeds the engine. This is the technology that's been flying fighter jets for years and, despite the hocus-pocus concept of your throttle hand not actually operating the throttle valves, the system renders exceedingly precise, smooth and instantaneous power delivery. Click on image to enlarge.
Another highly sophisticated element unique to the R1 is the electronically controlled intake funnel length. At 10,500 rpm (with the throttle position electronically indicating aggressive acceleration) the intake funnels feeding fuel to the engine expand from 65mm to 140mm, increasing intake volume by 40 percent. The result is a substantial hit in the upper spectrum of the tachometer which is suited more so to track day outings than any legal—or sane—application on public roads.
Titanium 31mm intake valves, new high-lift cams, light and strong nutless connecting rods all contribute to a quick-revving engine. High silicon-content, ceramic-composite cylinder sleeves help dissipate heat and reduce friction for high rpm durability. Radiator capacity has been increased 13% and married to an aluminum liquid-cooled oil cooler for stable, consistent operating temperatures. The stock titanium underseat exhaust system emits a kind of turbine sound when downshifting, perfect accompaniment for the omni-present MotoGP fantasy.
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