I've been noticing a midrange bog on my 2001 700 SRX. After driving it for a while and cruising at 70 to 75 miles an hour the sled feels like it's going to seize up and starts slowing down. I Immediately let off the gas and then throttle it but it has a hesitation or a bog and hesitates to accelerate just like the clutches are shifted all the way out or it is running out of gas in midrange. We took a 30 mile river ride yesterday and it seemed to run fine. On the way back it started this problem. It was approximately 35° out. I've been having this problem when the machine is run steady for many miles at a higher cruising speeds. This is when it becomes very noticeable but not when you're on a trail accelerating and decelerating constantly. The motor has some work to it. Some mild porting and the heads are shaved a little. We went up two main jet sizes when the motor work was done and the plugs look real good, not lean or rich. We did not change any other jets or make any other carb adjustments. The machine also does this with an aftermarket clutch kit, put together by Hauck using information I gave them on the sled modifications, and the stock clutch Kit. It's been 1500 miles on the sled since the work has been done to it. But like I say, after cruising for many miles at 70 to 80 miles an hour, the motor feels like it wants to slow down and when you give a gas there is very little response. Any ideals were to start. My friend was a Yamaha mechanic for 10 years and he figures it might be running lean on midrange and told me to turn in air screws slightly and he said this would richen it up. Haven't tried it yet though. I also have a new belt on it and spark plugs. Carbs have been disassembled and thoroughly cleaned. Problems still exists.