I have a kx500 2 stroke with a Keihin 39 mm carb. The bike was recently re-sleeved and put back stock except for the pipe. The bike starts easily but does not lean out. It ran as though the choke was on. So, I done some research and changed the Jets. This made the bike run better but not perfect. I have played around with various sized jets (pilot and main) and still have this problem. The problem I am experiencing is while in the low gears the bike runs flat or lacks power, kind of like its running rich, but I’m not sure. I operated the throttle at all ranges. Now when I change into third and on into the higher gears, the bike takes off and runs perfect. The power at this point is awesome, and I’m more than a little confused as to what might be making the bike act this way in the lower gears. I’m using the throttle pretty much fully open in both cases. Thanks for any suggestion in advance.