Yamaha YZF-600 R6

The YZF-R6 for 2003. Allegedly all-new and undeniably all-R6, it rolls into the most serious 600 class in years some eight pounds lighter and packing three additional horsepower. A radically refined aluminum chassis aims to top any 600-class cornering comparison, while its artfully sculpted skin keeps the silhouette fresh.

Starting out with a class-leading package makes radical change unnecessary. The story starts with a revamped ram-air inlet, feeding what Yamaha says is a more efficient pressurized airbox. Downstream, four YZF-R1-type 38mm throttle bodies provide the most predictable innovation: electronic fuel injection. Move deeper into the engine and changes are more subtle. Waging war against friction and pumping losses--power-sapping crankcase pressure fluctuations created by pistons flying around at 15,000 rpm--90 percent of the part numbers in the '03 R6 engine are new. Cams dial in higher lift, and valve springs are stiffened to match.

Yamaha engineers say the existing 65.5mm x 44.5mm cylinder dimensions are just fine, thanks, but the pistons get a 10 percent thicker top ring for less flutter and better sealing against hot, high-velocity combustibles. Crankshaft balance has been carefully recalculated, also. All that adds up to 117 claimed crankshaft horsepower at 13,000 rpm on Yamaha's dyno--123 hp with the requisite amount of fast-moving atmosphere crammed into the new airbox. Because more power means more heat, there's also a larger curved radiator, allowing 30 percent more airflow to keep everything cool.

The Deltabox III frame shows lessons learned from the '02 R1, along with some tricky manufacturing technique. Thanks to Yamaha's proprietary Controlled Filling (CF) aluminum die-casting procedure, the '03 R6 skeleton is allegedly 50 percent stiffer--on par with the R7 superbike chassis in terms of rigidity--and radically simpler to build, assembled with two welds rather than the 16 necessary to bond an '02 R6 frame. First used in manufacturing Yamaha's RX-1 snowmobile, CF casting technology lets engineers optimize the flow of molten aluminum into a die, maintaining precise control over the temperature of the die itself and drastically increasing the vacuum inside. With fewer air bubbles sneaking into the mix, aluminum bits can be thinner, lighter and just as strong. The computer-controlled CF process also allows engineers to cast larger, more complex shapes--quite a big deal when an '02 R1 is comprised of approximately 40 percent aluminum.

Wheelbase is status quo at 54.4 inches--another optimal number to R6 designers--but other chassis numbers were tweaked. The swingarm is 10mm longer, and the countershaft sprocket centerline migrates 10mm closer to its pivot point. At 24 degrees, rake is unchanged from '02, but moving the triple clamp closer to the rider stretches trail to 86mm--5mm more than last year--admitting that longer swingarm into the aforementioned optimal wheelbase, and adding a little composure to R6 steering manners, too. The CF process also serves up a lighter, simpler aluminum sub-frame.

Details? A new hefty little catalytic converter could have canceled some of that weight loss, but replacing steel muffler entrails with titanium created an exhaust canister that's 2.2 pounds lighter than last year. Created via a separate casting process, new five-spoke aluminum wheels are stronger, and will arrive with '02-spec radial rubber: a 120/60ZR-17 front followed by a 180/55ZR-17 rear.Prices are predictably vague as we go to press, but as long as nothing drastic happens to the Dollar/Yen relationship, the sticker price will be as close to the current $7999 tariff as Yamaha can get it. Expect to put your sweaty little palms on one in late December or early January.

Review

Allegedly all-new and undeniably all-R6, it rolls into the most serious 600 class in years some eight pounds lighter and packing three additional horsepower. A radically refined aluminum chassis aims to top any 600-class cornering comparison, while its artfully sculpted skin keeps the silhouette fresh.

Starting out with a class-leading package makes radical change unnecessary. The story starts with a revamped ram-air inlet, feeding what Yamaha says is a more efficient pressurized airbox. Downstream, four YZF-R1-type 38mm throttle bodies provide the most predictable innovation: electronic fuel injection. Move deeper into the engine and changes are more subtle. Waging war against friction and pumping losses--power-sapping crankcase pressure fluctuations created by pistons flying around at 15,000 rpm--90 percent of the part numbers in the '03 R6 engine are new. Cams dial in higher lift, and valve springs are stiffened to match.