Please bear with me, I am a bit of a dumbo when it comes to carbs and setting them. I have a 2004 XR650R (ED model ie: European) Stock carb and the bike is stock "uncorked". I live in the UAE ie the desert, at sea level .Winter temp around 25-28 deg C and Summer around 40-44 Deg C. Now stock jetting on the ED model is Main:#175 , Slow jet: #65 and clip position is 3rd from top position. If I look at "Erics" jetting charts it has the main at #168 Slow Jet at #65 and Clip in position 2. at high ambient and at around #175 ,#65 pos 3 at cooler ambient temp. I have just installed a PC T-4 slip on muffler (stock header) and it pops ever so slightly if I deccelerate suddenly (If I brake slowly to a stop ,no popping) Now that I have confused the crap out of all here are my questions. 1) With the stock setup, is my bike going to be lean or rich at higher ambient temperatures. 2) Will it make sense to use "Erics" jetting tables and choose a jetting setup ...say ..halfway between the lower winter temps and the higher summer temps. ie: the bike will run a bit leaner or richer whichever way the weather turns. or am I blowing smoke up my own arse with this?? 3) With the stock setup and the the new T4 pipe will the bike be rich or lean ? as the ambient warms up will it become richer or leaner? I hope there is someone out there with the patience to get my head around these questions...thanks!