The Yamaha FZR600 is a sports motorcycle produced by Yamaha between 1989 and 1999. It was the successor to the FZ600 and was replaced by the Yamaha YZF-R6in 1999, its last year of production and first year of production of the YZF-R6. It had a steel Deltabox frame and swingarm, similar in appearance to the alloy Deltabox frame introduced three years earlier on the 1WG FZR400. The FZR600 was discontinued in 1999 due to age of the design and the competing 600 cc sportbike offerings from Yamaha: The YZF-600R and YZF-R6. The four-valve Yamaha FZR600 engine was slanted forward in the frame. This was the basis of the Genesis engine and Delta Box frame concept, and helped to lower the centre of gravity and help centralise mass. This layout allowed the real fuel tank to sit behind the cylinders, low between the frame rails, and further aided with lowering the centre of gravity. Forward of this sat the airbox, with four 32 mm Mikuni downdraft carburettors, and all these assemblies were covered by a plastic cover dummy petrol tank. Unlike the larger FZR models, which had featured three intake valves and two exhaust valves per cylinder, the FZR600 had a four-valve-per-cylinder layout, necessitated by the different gas flow characteristics of the 600 cc engine over the 750 and 1,000 cc units in the FZR range. Many models came with the EXUP valve system, mandatory for units sold in California. This system located in the lower exhaust manifold helps maintain high back pressure at low engine speeds, and opens up more at higher engine speeds, giving the motor better mid-range power. The EXUP system was mainly found in US and some European models to compensate for the loss of power caused by emissions related modifications for those markets. Standard world market models produced, compared to about for EXUP equipped versions. The FZR600 continued in production until 1999. However, in some markets it was still marketed as the FZR600 in 1994 even though it was actually the closely related YZF600R, which was mechanically similar but featured an all-new steel frame, slightly modified engine producing 98 BHP, and different styling with the now famous "Foxeye" headlamps. The original steel-framed '3HE' FZR600 remained virtually unchanged throughout its production. In 1991 the FZR received a single trapezoid headlamp to ape its FZR1000 EXUP sibling, but Yamaha reverted to the twin headlamp design for 1993. In 1990, the rear wheel width was increased to 4 inches. In the same year the front brake calipers were upgraded to 4-piston units. In 1991 the FZR received a different swingarm, which was slightly fatter in profile. Aside from the minor mechanical changes, the paintwork and color schemes were the main change for each new model year, including the Vance and Hines special edition scheme that was available for 1992.
