Steer It Up!
By The TWMX Testing Staff
It¿s no secret that Honda¿s CRF450R has made a huge impact on the sport of motocross. Shuttling Ricky Carmichael to a perfect 24-24 series in the 2004 outdoor Nationals, and winning just about every magazine shootout since its 2001 inception, the CRF450R could very well be the best motocross bike of all time.
In 2005, the CRF450R once again won the TransWorld Motocross 450cc four-stroke shootout, but by narrower margins than one might expect. Suzuki¿s new RM-Z450 gave the mighty Honda a run for its money with great cornering and handling ability, but in the end it was the Red Rider that came out on top, thanks greatly to an amazing motor package. In fact, Honda engineers are so proud of the 2005 powerplant that they left it virtually untouched for 2006. Rather than focusing their efforts on messing with perfection, they focused their aim on further refining the handling of the CRF450R, with a large emphasis being placed on steering and cornering ability.
How did they accomplish their goals? Center of gravity. By lowering the overall center of gravity of their four-stroke beast, the technicians at Honda knew they could further improve the overall handling and steering capability of the bike. To do this, they started by lowering the frame rails that cradle the engine. Once that was done, the engine cases were changed to tilt the engine forward and lower the crankshaft a full 5mm compared to the 2005 CRF450R. The countershaft remains in the exact same position, however, which means the engine has rotated down in front¿ultimately lowering the bike¿s center of gravity. Additionally, these changes are said to reduce the chassis¿s roll figures by 2.7 percent, which contributes to even more responsive steering.
Because the cylinder now tilts forward, the ¿06 utilizes longer engine hangers to accommodate the extra distance. It¿s important to note, however, that despite its repositioned engine, the CRF450R¿s ground clearance remains the same, as the lowest part of the frame¿the area near the footpegs¿is unchanged.
With a relocated engine, the ¿06 carburetor is about 7.5mm farther forward than before, so the entire subframe was also moved forward 7.5mm. One might think that it would have been easier to just change the shape and positioning of the airbox to accommodate the change, but Honda engineers wanted no part of that, as they feel the design of the 2005 airbox is a large contributor to the motor¿s amazing performance. The exhaust system has also been reshaped as a result of the new engine position, but the overall length and volume of the remains the same. Continuing on with the same theme, the CRF¿s twin radiators have been mounted 5mm lower than last year¿s radiators, contributing to the bike¿s overall lower center of mass.
Other notable changes made to the ¿06 CRF450R include shortening the front fork tubes 7mm to reduce fork weight by 2.45 ounces. The fork tubes were elongated in the past to accommodate 20-inch front wheels for those who desired, but with that option now a thing of the past, the Honda engineers took this opportunity to trim some length and weight from the fork. The front wheel hub is now made of the same light and strong material introduced in last year¿s rear hub, and a new material is now used for the seat of the intake valves to improve valve wear and reduce intervals for servicing.
Although we don¿t have a ton of seat time on the 2006 CRF450R, the overall impression of the changes made to the bike are good, and our test riders are eager to spin more laps on her soon. When ridden back-to-back with our stock `05 model, we did notice significant improvements with the CRF¿s cornering ability. In places where our ¿05 felt a bit hesitant¿like sticking smoothly in ttight, rutted corners¿the new bike handles with authority. By focusing their efforts on lowering the 2006 CRF450R¿s center of gravity, Honda has continued to evolve four-stroke motocrossers, and the improved cornering ability of the CRF may be just what she needed to stay on top in 2006.