I asked greyracer couple months back about my new 09 yz450f running rough at 1/4 throttle and he suggested unplugging the tps and this worked. I did order a new needle for the carb but after 3 months on back order I gave up. Since then I have ridden the bike and on a fire road and in 4th and 5th gear at 1/4 throttle it was horrible, very rough. I looked on JD jetting web site and on the FAQ section it descibed this exactly but about the Wr450's and he even mentioned unplugging the TPS. it went on tho say this is normal and this was to prevent the bike from over-heating and it is an ignition thing. Is this true because it is very annoying? I know these bikes are not made to be ridden at a steady 1/4 throttle but sometimes it happens and you would think it would affect the acceleration going through that point of the power.