2006 Yamaha YZ250

2006 Yamaha YZ250: The SSS Suspension Era Begins

The 2006 Yamaha YZ250 was a significant update to the aluminium-framed platform introduced one year earlier. The basic 249 cc two-stroke engine and aluminium semi-double-cradle chassis remained, but Yamaha made one change that would become hugely important to the model's reputation: the introduction of KYB's Speed Sensitive System, better known as SSS suspension.

The new 48 mm KYB SSS fork was designed to control damping primarily according to fork speed rather than simply fork position. In practical terms, this gave the front end a more controlled and predictable feel over braking bumps, jump faces and square-edged impacts while still remaining compliant over smaller chatter. The design became one of the most praised production motocross forks of its era and remained closely associated with Yamaha's YZ range for years afterward. Owners servicing these forks can use the MXOwners fork oil reference when checking oil and setup information.

The rear KYB Monocross shock was also revised to work with the new fork and aluminium chassis. With adjustable spring preload, rebound and separate low- and high-speed compression damping, the YZ250 offered a broad setup range for riders of different weights and skill levels. Proper sag, linkage condition and shock servicing remain essential on older examples, and the MXOwners rear suspension reference can help when working through rear-end setup.

The engine remained the familiar liquid-cooled 249 cc reed-valve two-stroke with Yamaha's YPVS power-valve system. Fuel continued to be supplied through a 38 mm Keihin PWK carburettor, giving the YZ250 the sharp throttle response and strong midrange that helped define the model. Owners maintaining the original induction system can use the MXOwners carburettor reference when looking at replacement or repair options.

Yamaha continued to specify premix lubrication rather than oil injection, with a 30:1 petrol-to-oil ratio using Yamalube 2-R or an equivalent racing two-stroke oil. The gearbox uses a completely separate oil supply, so premix oil and transmission oil perform different jobs. The premix lubricates the crankshaft, piston and cylinder, while the gearbox oil protects the clutch and five-speed transmission.

The aluminium frame introduced for 2005 remained central to the bike's character. It was lighter and more rigidly controlled than the old steel chassis and gave the YZ250 the modern layout that would carry forward through many later model years. By combining that chassis with the new SSS suspension, Yamaha created a package that became known as much for its handling as for its engine.

For modern owners, the 2006 YZ250 is particularly significant because it represents the point where the familiar aluminium-frame YZ250 gained the suspension design that became one of Yamaha's strongest advantages. Replacement chassis, engine and suspension components can be checked through the MXOwners parts finder when rebuilding or restoring an older machine.

The 2006 model was therefore not an entirely new generation, but it was far more than a routine annual update. The arrival of KYB SSS suspension completed much of the transformation begun with the aluminium frame in 2005 and helped establish the basic formula that allowed the YZ250 to survive while many rival Japanese 250 two-strokes disappeared.