2007 Yamaha YZ250

2007 Yamaha YZ250: Refining an Already Proven Two-Stroke

The 2007 Yamaha YZ250 was a refinement year rather than a major redesign. Yamaha had made the big chassis change in 2005 with the aluminium frame and followed that with the important KYB Speed Sensitive System suspension update in 2006. For 2007 the company concentrated on detail improvements while leaving the successful basic formula intact.

The 249 cc liquid-cooled two-stroke engine remained fundamentally unchanged, retaining its reed-valve induction, Yamaha Power Valve System and 38 mm Keihin PWK carburettor. That combination had already given the YZ250 a reputation for strong, usable power and crisp throttle response. Owners maintaining the original fuel system can use the MXOwners carburettor reference when checking replacement or repair options.

The aluminium semi-double-cradle frame also carried over, as did the highly regarded 48 mm KYB SSS fork and link-type Monocross rear suspension. By 2007 Yamaha had reached a very polished suspension package, and correct setup remained one of the bike's greatest strengths. Owners servicing the front end can use the MXOwners fork oil reference when checking oil and setup information.

Yamaha continued to specify premix lubrication at 30:1 with Yamalube 2-R or an equivalent high-quality racing two-stroke oil. The five-speed gearbox used a separate oil supply, so transmission oil and premix oil performed completely different jobs. The MXOwners premix calculator can help when preparing accurate fuel mixtures.

Historically, the 2007 model is important less because it introduced something revolutionary and more because it showed how complete the YZ250 package had become. While other Japanese manufacturers were increasingly shifting attention toward four-strokes, Yamaha continued refining its 250 two-stroke. That long-term commitment helped the YZ250 become one of the most enduring motocross motorcycles ever produced.