My new '02 XR650R has 625, 85% dirt miles on it. It came from a notable Honda dealer set up with the Honda Power-up kit installed. I put a UNI air filter on and removed the backfire plate. I have not adjusted anything. The needle is supposedly in the stock position. It "misses" when I roll the throttle on over fast choppy terrain at lower RPM's. The jet is a #168 for the 4,700 to 6,000 foot elevation I generally ride, although it can extend to 10,000 plus feet. It generally runs flawlessly, especially at higher elevations and on smoother ground. I have been told by one Honda shop that this jet is too lean and another Honda shop says it is perfect. The sparkplug tells all and is burning light tan with a dusting of carbon indicating a good jet, no? The majority of my riding is at the lower elevation. What do you think is happening? Thanks in advance for your tips.