Have bike at mechanic getting carbs rebuilt. Carb kits purchased were bought from VintageCB.com kit came in manufactured by Napco Corp Japan. (APCO) After getting into 1 carb found some scorching on needle. The # on needle is F2D51E. The replacement in the kit # Y41. Appear to be same length but the point on the Y41 is shorter than the original. Unsure we should use it. Carbs are PD41. Where can I get the original. Shop manual shows the F2D51E is correct. Can't find any info on specs of either needle.Help is appreciated.