Is it a used needle valve assembly? What kind is it? You obviously have the wrong needle for that spray bar. Need more details.
  Type at you later,
  Dan McEntee

   Compare the new needle to the old one. The needle needs to be the same length. If it stops, and still too rich, the needle is too short. These tend to vary, especially on the last run OS made of these. I have seen all sorts of stuff. It is supposed to be the same needle from FP.20 through LA.46. Measure and compare everything for anything bent or distorted from the impact. This is a good time to mention OS needles are not the same as Enya, either. These things can have varying tapers on them also. I have taken OEM  OS needles and filed steeper, more sharp points of them in order to get a better adjustment. Sometimes the needles are not installed in the knurled hub properly either. Look over noth complete needle valve assemblies for any differences.
  Type at you later,
   Dan McEntee

It could be that this one got bent a little in the crash I referred to.  I get my needles now from Bobby Brooks.  shtterman@aol.com.

    Hi are made by Enya but are supposed to be to OS specs, but still worth a close comparison. I got a few and did some checking against what i had, and determined that there was old OS FP series that was one size that came with a black and white header card. Then there was the familiar white and blue header card that we have been seeing since the LA series came out. They differ on outside diameter. I got some from Bob brooks when he first had them available and found that there was a slight issue with the way the nuts fit the spray bar, I think it was. just a little loose, but a OS nut fit the same as it did on an OS spray bar. His needles seemed a bit better than the OEM units did also. I wanted to take the comparison a little further but got side tracked and lost momentum on the project. I had a spray bar on a Norvel .061 get bent after repeated lawn dart landings in the trainer that it is in, and got the same effect as you. Got the spray bar out and got it straightened and functioning again. I still have some suspicions about the last run of OS OEM needle valve assemblies.
  Type at you later,
  Dan McEntee

Thanks Dan for the reply.  I've got to try again one of these days.  I am a busy father and pastor.

    Yeah, I can understand. Just wanted to pass on what I've found. The problems some experience may not be their fault. The typical OS needles used to be pretty sharp, almost like, well, NEEDLES!! Nice long tapers and such. . Some of the last ones I opened are down right blunt, and stubby , but they can be dealt with. I have a suspicion that, and haven't figured out a way to prove it, but the last run of the FP .20-LA.46 NVAs may have been made from excess .15 size needle spray bar stock, but need to sit back down with my parts box and calipers to figure that out.
   Type at you later,
  Dan McEntee