I bought my son a hardly used 2007 TTR90. It did not run when I bought it so I cleaned the carb and got it running. It ran ok but not right. The throttle was always really touchy. Recently it got so bad you could not turn the throttle at all, it would just die. I cleaned the carb several times. I finally had to break down and take it to a shop. They said it would just be a blocked jet and most people don't get them clean. After them taking it apart 4 times, replacing the jets it runs better but they are still working on it. They said the carb was clean as a whistle (so I feel better that I did my part right). The bike is stock. Why am I having so much trouble, it is all Yamaha bikes? I have two Honda bikes that are a lot older with no issues. I think this will be the last Yamaha in the family. Anyone else having the same issues? Thanks.