Stock Jet needle is position (JN) = OBDUT-4 I think. I am at 800 ft., and 20 to 40 F. I have ridden the bike once, and it was great except it still has an off idle bog. I have not been on a track yet, just in my yard, but don't want thet off idle bog!!!! When I had a 2000 YZ426 that OFF IDLE BOG thru me over the bars in a set of 6 large woops. I have ordered the following Jet Needles: 5NL-14916-EN-00 (#OBELN) for YZ250F 2003 5TJ-14916-D1 #DUQ From my manual for richer jet. 5TA-14916-JN-00 (#NDJN) for (YZ-450F) 2003 might try: NCVQ-4 or 0BDRR-4.... I have also ordered the #100 PAJ and a #72 chock jet. I know the #72 chock jet will not help my problem, just thought I would get it Cause UT says it helped his starting. When these jets come in, what order should I change them out? I know Taffy did a lot of testing on jetting on the 426 hope he sees this post. When the snow and rain quit and the jets get to me I will be testing these. How to go about it is the real question?