611 Series Needle Jet Size Y-2. This item fits Mikuni BDST 38 Downdraft CV carb as fitted to Ducati models. This is the stock replacement needle jet for Ducati Monster and other carburetored models where wear inside the NJ, usually caused by aftermarket titanium needles, creates a rich mid-range condition. The Mikunioz back board with 1 and 10mm increments may help you with identification but if it doesn’t match up, it wont and if in doubt please call our office before ordering. No returns on jets.