06-09 YAMAHA YZ450F: JD Jetting Jet Kit James Dean designed the JDJetting kits so that you don&#39;t have to be an expert to get professional high performance results!The James Dean custom jetting kit is designed to improve throttle response throughout the range by using specially made multi-ta These are based on the most popular settings used by new generation MX and off-road riders around the globe and the results are impressive. Exceeds the performance of standard two-stroke and four-stroke jetting, and other factory needle options.You can&#39;t buy this level of performance from the O.E.M. factory or other aftermarket suppliers. JD&#39;s testing and research will provide the performance you need.Exceeds the performance of other standard factory needle options and technical support is provided.Low and high altitude custom designed triple-taper needles.Main jets included.Spare need