We had a large temperature swing in the last day in the NE and I'm afraid my quest for the elusive unicorn, Jetting Nirvana so aptly put by Clark has gotten a better lead on me. You know, the bike runs awsome now but I have this box of jets and a boat load of tools. I just can't stop trying things !! I also installed a PMB insert last night while it was 65 - 70 and VERY humid. The rest of the week mid 30's as the high. That'll give me a good excuse. Hon, I can't leave the garage, the temperature dropped and I ned to change my jets... When I raced 2-stroke karts I constantly logged data like tire pressure, temperature etc.. I also used an air density gage with temperture compensation to give me an idea which way to adjust jetting. If one were to use the same gage and log the jet settings with on a wr450 shouldn't it repeate and make for eaiser setup? (added) The 50 degree temp drop brought back the low end bog Help me, I can't stop messing with this thing!!!