1. Fork springs. The stock 0.46 Kayaba fork springs are too soft. We switched to 0.48 or 0.49 kg/mm springs.
2. Fork valving. With stiffer fork springs installed, the midstroke valving was too light. We sent the forks to Pro Circuit to be revalved. www.procircuit.com
3. Shock spring. For riders over 175 pounds, the stock 5.4 kg/mm shock spring is fine (it will work for riders up to 210 pounds). Lighter riders (under 175 pounds) will need a softer 5.2 kg/mm shock spring.
4. Shock linkage. As it sits, the 2009 CRF450 stinkbugs. Our best solution was to swap out the stock 144mm shock linkage for a Pro Circuit 146mm link. It lowers the seat height and stiffens the initial part of the shock’s stroke (but does not affect the end of the stroke). www.procircuit.com Many suspension shops offer to shorten the Honda shock by 3mm when they revalve it.
5. Clutch. Honda’s four-spring 2009 clutch doesn’t have as much clamping pressure as the six-spring 2008 clutch. After suffering clutch issues, we installed a Hinson six-spring clutch kit. A cheaper, but not as thorough solution, is stiffer aftermarket clutch springs. These aggravate the narrow actuation point of the clutch arm, but are better than burning up plates). www.hinsonracing.com
6. Gearing. Riders of every skill level felt that the stock 13/48 gearing was too tall. Novice and Vet riders added one tooth (13/49), while Intermediate and Pro-level riders went for 14/52 gearing (this is lower than stock, but not as low as 13/49).
7. Exhaust. The 2009 Honda CRF450 cried out for an aftermarket exhaust pipe. In stock trim, the CRF450 peaks at 51 horsepower at a rather pedestrian 8500 rpm. Aftermarket pipes add two horsepower (or more) and move the peak up to a more usable 9500 rpm. MXA tested five different exhausts and all made more power than stock. In this test we used the Yoshimura exhaust. www.yoshimura-rd.com
8. Miscellaneous. We removed the disc guards (front and rear). Ride Engineering makes a replacement wheel spacer, but we just hacksawed the plastic guard off the stock spacer (www.ride-engineering.com). We gave up on reprogramming the ignition because the gains were insignificant (except for some tests rider who retarded the ignition at low rpm to cut down on the bark). We ran a 110 rear tire (not the 120). We drop-kicked the 742FA front tire and ran DeCal works number plate graphics (www.decalmx.com) and Acerbis footpeg boots (www.acerbis.com).