Cycle News is a weekly magazine that covers all aspects of motorcycling including Supercross, Motocross and MotoGP as well as new motorcycles
Issue link: https://magazine.cyclenews.com/i/128389
Can the Honda CRF4SDR actually get any better? By THE CYCLE NEWS STAFF PHOTOS BY KIT PALMER would you feel if someone from Honda put the 'OS CRF450R in front of you and said, "Here, make it better!" - and without drastically driving up cost, mind you? Now you know how the engineers responsible for the '06 CRF450R must have felt. After all, the 'OS CRF450R is considered by many as the best all- H OW around production motocrosser ever built. So, it shouldn't be a surprise that half the riders at many of the outdoors MX Nationals are CRF450R-mounted. The bike is a Sunday favorite for its outstanding motor, solid handling, great comfort and excellent suspension. Throw in Honda's reputation for quality of craftsmanship, and you have a 450cc four-stroke by which all others are judged. So, how do you improve on that? Well, since there is no such thing as the perfect motocross bike, Honda engineers took a long, hard look at the 'OS CRF450R and determined that if there was one area that could perhaps use some improving, it was in the turning department. WHAT THEY DID Hondo did its homework when it came to improving upon the already proven CRF4S0. The few slight changes helped to make the bike even better. 62 AUGUST 3, 2005 • CYCLE NEWS Honda's answer to the CRF450R's turning "problem" was to tilt the engine forward in the frame. The countershaft remains in the same position as before, but the crankshaft gets lowered by 5mm. The reason for this is to lower the bike's center of gravity (CG), thus giving the front end improved response and better bite in the turns, something some riders have complained about ever since the 450F first came out in 2002. In case you were wondering, no ground clearance was sacrificed, since the lowest part of the frame, the area near the footpegs, was unchanged. To help lower the CG even further, the radiators were also mounted 5mm lower. The forward rotation of the motor, as minor as it might seem, brought with it many challenges for Honda's team of engineers. The main problem: to reposition the motor without tampering with the CR's beloved power characteristic and handling qualities. When you reposition the motor, you cause a dominolike effect elsewhere around the motor, since things like the exhaust headerpipe, carburetor and airbox no longer fit, and these are important issues that can affect engine performance. So, many of the other smaller changes Honda made to the '06 450, like a new headerpipe, were designed to keep the bike running just like it did last year. As a result, the '06 also got new engine cases, longer engine hangers and redesigned lower frame rails, again, all to accommodate the new engine placement. There are some other minor changes as well. Closer inspection reveals a new kick-starter and a new exhaust pipe mount that is now attached to the subframe instead of the mainframe. This, Honda claims, was designed to give the 450 improved chassis feel, via new fleXing characteristics of the subframe. To improve reliability, the CR got new intake valve seat material, which features a finer-grain structure in the metal. The CRF also got a new water-pump impeller, which is said to double the life of the seal. Evidently, the old impeller created unwanted backpressure between it and the seal. Honda solved this problem by drilling a small relief hole in the impeller, which lessens the