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Yamaha YZF 1000 R1-SP

For 2006, the swingarm was extended by 20 millimetres (0.79 in) to reduce acceleration instability. In this year, Yamaha also released a limited edition version in original Yamaha racing colors to celebrates its 50th anniversary.

The model (LE/SP) featured a Kenny Roberts replica paint pattern with yellow and black paint, and front and rear custom Öhlins suspension units developed by the same team as the YZR-M1 MotoGP bike. Custom forged aluminum Marchesini wheels specifically designed for the LE shaved nearly a pound off the unsprung weight. A back torque-limiting slipper clutch, and an integrated lap timer rounded out the package, making the LE virtually a production racer. Only 500 units were made for the United States.

Yamaha's R1 has been tweaked and massaged for 2006 to produce a claimed 2.2kW more power at 12 500rpm. To give you an idea of the detail work this involves, the intake valve guides have been shortened by 5mm to 27.5mm.

This allows a smoother, straighter intake port and improves intake gas flow; Yamaha says it also reduces frictional losses on the valve stems but I somehow doubt the difference would be measurable.

The cam chain tensioner has been revised and the clutch boss modified for better oil flow to the clutch assembly.

Its chassis has also been nipped and tucked to move the weight bias one percent further forward and extend the swing-arm by 20mm; the frame thickness has been modified to change the frame rigidity balance without affecting vertical rigidity

The front suspension has been modified to suit the revised weight bias, including a new lower triple clamp. The rear engine mounts have also been revised and the swing-arm pivot has been moved to optimise the effect of its increased length on the handling – but that's not the big news.

The big news is that for the first time on a Japanese litre-class sports bike Yamaha has seen fit to build, alongside the standard model, a limited-edition "SP" (sport performance) version dripping with the special components American journalists used to call unobtanium because you just couldn't get them in the US.

SPs are generally low-volume, homologation specials, sold to the public in just sufficient numbers to satisfy racing regulations

. In this case only 500 R1 SPs will be produced to legalise its special suspension, wheels and slipper clutch for World Superbike competiton use.

The slipper clutch does exactly that – it slips under hard engine braking to reduce rear wheel chatter and uncontrolled slides. It also makes possible hair-raising clutchless down-changes without upsetting either gearbox or chassis composure.

Apart from the special clutch, the engine is standard but the running gear is really special, based on world-class components from Swedish suspension specialist Öhlins, carefully set up to match the R1's chassis characteristics and tuneable through a wider range of adjustment than the unit on the "ordinary" version – believe me, there's nothing ordinary about any R1!

The rear suspension has a hydraulic pre-load adjuster that allows quick and accurate settings "on the fly" as well as a compact ride height adjuster in a relay arm on the suspension linkage. This allows your pit crew to raise or lower the rear ride height without affecting the spring preload or static sag settings.

The 43mm Öhlins upside-down forks have a TiN coating on the chrome sliders to minimise stiction while the outer tubes are also anodised gold. They're adjustable for preload, compression and rebound damping through a greater range of parameters than the "standard" units.

By far the most eye-catching special components on the SP, however, are the Marchesini forged aluminium rims, with the same Y-shaped spokes as used on Valentino Rossi's M1 MotoGP machine.

Each is 400g lighter than a cast rim of equivalent strength which Yamaha says is responsible for the R1 SP's superior handling and road-holding, together with the revised rigidity balance of the frame.

The R1 SP will only be available in a distinctive colour called Gun Smoke, with gold wheels, gold anodised underseat silencers and and a special gold-coloured Triple Tuning Fork badge on the fuel tank.

Each of the 500 R1 SP's will have a small plaque engraved with its production number to underline its exclusivity.