Hi, I feel bad posting as I am sure the answer to this question is in the forum somewhere. I have done considerable reading to see if I can determine what could be the cause of my problem. I have a 2007 DRZ400sm that I purchased last year. It has a FCR MX Sudco carb on it. A yosh pipe rs-2 full system and K&N air filter. The bike seems to idle O.K. now that I have adjusted the fuel screw 2 - 2.5 turns out. However at times it seems to studder a constant throttle around a 1/8 to 1/4 throttle position. The engine seems to miss, my guess is that I am running a bit lean at this position. If I flick the throttle the bike seems to rev nicely, also the bike will pull nicely under heavy acceleration. I live in Ontario Canada and the temperature variation at this time of year is quite high. It seems like in the morning the bike runs better then when it is warmer in the afternoon. I have no clue what the current setup is, however I would assume that it is as delivered from TT. I have at this point only been playing with the fuel screw as I am afraid to make the bike worse but just tinkering without a plan. What are the steps that I should take to first diagnose the root cause?