The boys in blue are at it again. Yamaha brings some modest upgrades to its motocross lineup, revamping the YZ450F and YZ250F for 2012.
The YZ450F already stands apart on the motocross scene with its rearward-slanting cylinder, the Yamaha claiming improved performance from its offset cylinder and centralized weight. These revolutionary design elements have become fundamental to the 450F and remain unchanged. But to keep the YZ450F one step ahead of the competition, the 2012 model will offer revisions to its fuel injection, suspension and tires. Aesthetically the model also gets new color profiles, which include black rims and a gold-colored drive chain.
One thing Yamaha has done for the new model year is update its fuel map and optimize the ignition timing. The goal was to create a smoother throttle response and generate more low to mid-range power with improved roll-on performance. The 2012 YZ450F also includes a 42.0mm longer silencer with reduced sound output in keeping with new AMA Racing regulations which limit exhaust to 94db.
Yamaha claims the updates to the 450F provide smoother throttle response and better low to mid-range power.
Shifting on the 2012 model was given a boost by changing the locating pin to make the shift bar more rigid. The claimed result is more precise shifting on the 450F, particularly between second and third.
Both the front fork and rear shock have been tweaked to improve bump absorption and to reduce dive while cornering. Up front the fork is revalved for low to mid-speed compression damping. Meanwhile, the shock not only has revised rebound characteristics, but also gets a new valve setting for more high-speed compression.
Dunlop Geomax MX51 tires replace the existing D742FA and D756 rubber, with Yamaha touting improved traction as a result. The 2012 YZ450F is also adorned with black rims on its blue bike instead of the traditional silver.
In addition to these updates, the GYTR Power Tuner returns for the 2012 YZ450F which allows users to adjust fuel and ignition maps manually. The device is extremely useful for those who wish to squeeze the most out of their bike on those weekend trips to the track. More than nine points are customizable, and users can also get info on engine running time, water and intake temperature, throttle position and rpm.
The YZ250F has several key changes to its engine and frame, giving it more top-end and strength in its chassis.
2012 Yamaha YZ250F
The Yamaha YZ250F is hitting dealer floors in 2012 with a host of beefy upgrades to the nimble motocrosser. New design elements are found throughout the frame, engine, suspension and gearing – giving the 250F an overhaul for the upcoming year.
Yamaha first started with the frame by adding a three-box tank rail section instead of its original two-box design for increased rigidity. The frame design also includes a new swingarm pivot point and new engine brackets for more predictable handling.
Housed within the new frame design is a re-worked engine. Yamaha opted for a lighter piston, piston pin and wire circlip. Yamaha claims the new piston gives better performance by reducing overall mass and friction, providing more power from 8000-12,000 rpm. Yamaha engineers also took into account vibration on the 250F, revising the crankshaft balancer to reduce the vibes felt at several key touchpoints including the handlebars, seat and footpegs. In addition, the balancer shaft is now optimized for the lighter piston, which further reduces vibration.
Biggest news for the 2012 model is what’s not changed, as the YZ remains the lone 250 to shun electronic fuel injection. Yamaha did tweak the carburetor, however, boring it out another 2mm, and a high-flow air filter cage has been fitted inside the 250F to enhance top-end performance. CDI settings have also been reformatted to give the bike better throttle response in the mid to high-speed range, and a new silencer with a smaller outlet is designed to meet AMA Pro Racing sound regulations.
Up front the KYB Speed Sensitive System fork is revalved and is now offset by 22mm. The outer tube has also been enhanced for 50% more rigidity, and the steering stem was made longer. The spring rate on the fork is now 0.46kg. The 250F’s rear shock sees new rebound damping and a new swingarm adds more strength to the axle block. Yamaha touts that these changes add more refined damping character and improve bump absorption, allowing for more aggressive sessions on the track.