1. Gearing. Swapping the stock 50-tooth rear sprocket for a 51 was the cheapest fix made to the 2009 KX450F. Gearing the bike down lessened the gap between third and fourth, moved third gear closer to second, and most importantly, moved second gear down so that short-shifting was more accurate.

2. Chain guide. Switching to a larger rear sprocket quickly turns the chain guide into shark bait for the chain to chew through. We ate through the bottom chain guide in three hours, so we installed a bulletproof T.M. Designworks chain guide. While at it, we also installed a T.M. Designworks chain slider to prevent the chain from eating through the top of the swingarm.

3. Axle nut. Hate is a strong word, but it’s not strong enough for our feelings towards the cotter pin used on the rear axle nut. The MXA wrecking crew threw the cotter pin in the trash and switched to the self-locking rear axle nut from a Honda CRF450.

4. Exhaust. The stock 2009 KX450F exhaust system was extremely loud (99 dB), so we opted for Pro Circuit, DR.D, FMF or Two Brothers race systems on our KX450Fs. All of them lowered the volume and greatly improved the mid-and-up power.

5. Triple clamps. Kawasaki’s engineers recognized that they had a front end push from center out in corners, so they changed the fork offset on the 2009 KX450F (from 24mm down to 23mm). It wasn’t enough. We switched to Pro Circuit’s 22mm offset clamps, just like their race teams do, and found a solution to the problem.

6. Link. Due to a soft initial part of the shock stroke, the 2009 KX450F rear has a tendency to wallow under a heavy load. The Pro Circuit link dropped the height of the rear end and stiffened the initial part of the stroke, which helped the Kawasaki to track straighter. The Pro Circuit Link is used by almost every National KX-F racer.

7. Graphics. The MXA wrecking crew loved the look of the 2009 KX450F?that is, until the plastics became scratched and the graphics began to tear. We made an aesthetic improvement to the KX450F by slapping on the N-Style Paint graphics kit. We also used DeCal Works preprinted numbers to ensure a clean look.

8. Fork guards. We went through fork guards like they were made of plastic…or more accurately, brittle plastic. We felt that aftermarket guards from Acerbis ( or UFO ( were more reliable, but went with LightSpeed ( carbon fiber guards instead. Additionally, the radiator shrouds and side panels always seemed to have a crack in them whenever we looked at them.

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