Dave,
After I modified the throttle barrel I put it in. Set the regulator to flush with casing. Started up, let it warm up then set the High speed needle about 300 from max. Then brought it down to idle and it would sit there and hold an 2100 idle for about 10 seconds then speed up approx 500 to 800 rpms. The engine 8 out of 10 times would die when you were going from max throttle to idle. I tried turning the regulator out and resetting the top end. I just could not get it to run reliable. Borrowed my buddies throttle barrel out of his newer NC which had a larger hole then my original. I installed it, set regulator to flush with casing. Started it up, set high needle, brought it to idle, It was a tad rich, 1/4 turn in on regulator and the engine was purring like a kitten. I guess the moral of the story is that I should have started out just slightly enlarging the hole to find where it ran the best. Do you you have any new thorttle barrels in stock for the NC? If so how much? I need to get one so I can give my buddies back. Thanks