For some reason this information is not getting out to everyone, and I think it should be. This is what I consider vital information. These are my opinions, before you start challenging me on this info. Yes, you can buy your own jets rather than the JD kit. JD kit has tuning info, multiple jets, and SUPPORT. ** JD jet kit: corrects lean condition, and comes with multiple needles for multiple altitudes. No apump parts. No leak jet. ** Leak jet: you need to go down to a 55 or 50 to get the pump to squirt long enough, to work correctly. Increases duration of squirt. ** Apump diaphram and spring: replace only if your bike sits alot, or, if you have recently 'mistakenly' used carb cleaner on the carb. ** Apump mod: you can add an o-ring to the apump linkage, but a Merge Racing Detent spring upgrade works better, and lasts longer. Improves direct connection with throttle linkage. Pre 2008 models only need this. ** Apump adjustment: not required on all bikes, but good to check: apump linkage arm should touch throttle linkage arm, then back off 1/2 a turn. That is your starting point for the timing. Timing is about squirting just below the slide, and never hitting the slide.