Kit contains all the carb parts you need to perform the popular RD350 / RD400 carb mod. This modification is referred to as the Dave F carb mod and is used for bike with expansion chambers and performance air filter. Kit includes:(2)169PO Needle Jets,(2)5DP7 Needles, Main jets 180-220×2,(1)5/64 Drill bit. Main jets included are the approximate range, your specific application may vary depending on engine modifications, intake, porting, etc. If you are unsure of correct jetting, seek tuning advice. You can download instructions for this modification at the below link.