For those of you that are on the never ending quest for carburetion ambrosia, I have something that may help you succeed. The factory pro emulsion tube…… What is the emulsion tube? It is the tube that the main jet is threaded into. It emulsifies (mixes, atomizes etc.) the fuel as it gets pulled into the airstream of the carb. http://www.factorypro.com/products/Factory_Pro_HDJ_emu_hi_disp.html I have been playing around with different carb settings since I bought my 08 YZ 450 in Dec’ of 2008. I have played with main jets, pilot jets, needles and their positions. I got the bike to work great but it seemed that the needle position never gave me the crisp lower midrange that I was searching for. Below are my current settings 45 Pilot Jet 2.5 turns out on the fuel screw 165 Main Jet Stock needle 3rd clip Factory Pro emulsion tube I ride California desert at sea level and mountains of northern Baja with the same jetting. I did some websearch and found that there is a company who makes their own emulsion tubes which help increase the efficiency of the main circuit in the FCRs. Zip-Ty Racing also endorses their product and uses them in some/most of their race bikes. I ordered one from them over the phone because their website is a bit confusing, but none the less they have some great info on there. The installation was as easy as swapping out a main jet. Remove the 17mm float bowl plug, then use an 8mm to remove the emulsion tube. Swap the main jet to the new emulsion tube and put it back in. It takes about 5 minutes. I put a drop of gas on the o-ring of the new emulsion tube just to help it slide in. The results were not mind boggling but it did exactly what I was looking for. It cleaned up the off idle to ¼ – ½ throttle response. I also noticed that the off idle bog is better but not fixed. I highly recommend this emulsion tube to help clean up the lower to midrange throttle response.