Yamaha, the well-known Japanese motorcycle manufacturer, introduced the YZF R1 in 1998, setting standards for sport bike performance with it. The company reworked the bike in 2004, and then revised it again in 2007, switching its long-established five-valve head for a four-valve one. This model was carried over for 2008. The company made changes to the R6 in 2008, making it more competitive on the racetrack, and kept its R6 S model largely unchanged from its 2003 design.
The YZF R1, R6, and R6 S are all middleweight sport bikes. The R6 and R6 S have engines that displace 599 or 600cc; the R1, true to its liter-bike origins, displaces 998cc. All have liquid-cooled, horizontal in-line, four-cylinder, four-stroke engines, with a DOHC valve configuration with four valves per cylinder. All are fuel injected. All have six-speed manual transmissions with chain final drives.
In terms of suspension, the YZF models differ in some key ways and in other ways are virtually identical: The R1 and R6 S have inverted front forks with adjustable spring preload and rebound damping; the R6 has a telescopic fork with adjustable rebound damping. Twin-sided swing arms with adjustable preload spring shocks provide the rear suspension on all models.
Like the engine size, the dry weight of the YZF bikes varies, ranging from 357 pounds for the R6 and R6 S to 390 for the R1. While all have hydraulic dual disc brakes in front, the R6 S has an 11.7-inch disc; the other two have 12.2-inch discs.
All three models are compact and lightweight and feature sharp handling, making them highly regarded all-around sport bikes.