Flat top: Once the 2009 Honda CRF450 reaches 8200 rpm, where it makes its peak horsepower, it stays at that horsepower for
the next 3000 rpm. This is the flattest top-end powerband we have ever ridden. Overall horsepower isn’t earth shattering.
downtube. The head pipe length is 1106mm (it was 976mm). The tuned length of the pipe was 1361mm, but is now 1477mm. Sight glass: A dipstick on the left side of the engine replaces the previous sight glass. Q: HOW DOES HONDA’S FUEL INJECTION DIFFER FROM SUZUKI’S AND KAWASAKI’S? A: Very little. All three use Keihin throttle bodies with 12-port injectors, magneto/capacitor charging systems and a handful of sensors to provide info to the ECU. As similar as they are, they do have unique features. (1) The CRF450’s throttle body is 50mm (Kawasaki and Suzuki have 43mm throttle bodies). ( 2) Honda and Kawasaki use 50 psi fuel line pressure (Suzuki uses 42 psi). ( 3) Honda’s fuel injection system’s sensors monitor throttle position, intake air temperature, coolant tempera- ture, intake air pressure and gear position. Suzuki moni- tors the same things, plus it has a tip-over angle sensor. Kawasaki monitors everything that Suzuki tracks, plus it has a crank position sensor. ( 4) Honda and Kawasaki both offer optional software and plug-in programmers for around $350 that allow the fuel injection system to be altered. ( 5) All three bikes have their fuel pumps in the gas tank, but Honda and Kawasaki use rotationally molded plastic gas tanks, while Suzuki uses an aluminum tank. Fuel capacity on the Honda is 1.5 gallons (1.8 on the KX450F and 1.6 on the RM-Z450). Q: WHAT ABOUT THE JETTING? A: There is no jetting. The only thing a rider has control over is a 50-click idle adjustment screw that changes the air mixture slightly (it doubles as the choke knob). It is set at 1800 rpm.
(09) RACE TEST