This shorter stroke diaphragm has a longer center stem for less fuel delivery. Similar to the diaphragm used on some stock Honda models.

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James Dean designed the JDJetting kits so that you don't have to be an expert to get professional high performance results!! Even better, technical support is provided. The James Dean custom jetting kit is designed to improve throttle response throughout the range by using specially made multi-taper needles. 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 2-stroke and 4-stroke jetting, and other factory needle options. Low and High altitude custom designed triple taper needles. Main jets included. Spare needle clip. Dyno tested. Developed and tested from sea level to 12,000 ft elevation. You can't buy this level of performance from the OEM factory or other aftermarket suppliers. JD's testing and research will provide the performance you need.