GU17939167 Dellorto float needle and seat size 250 for PHF and PHM series carburetors used on Guzzi, Ducati, Laverda and other brand bikes. The 250 size is normally used on the mid-valve Guzzi touring models of 850, 1000, and 1100cc displacement. Tip: these needles have spring loaded retainer heads which commonly fail, requiring replacement.
Guzzi used part number 17939167 for 1000 Convert with PHF carbs, Mille GT, 850 T5, 1000 G5 with PHF carbs, California II with PHF carbs, SP1000 with PHF carbs, California III, CX100 with PHF carbs. Check your existing seat for the number.
Common to nurerous Ducati models, using part number 075527649