My son's TTR-90 has always been a pain in the rear to start and then to get it to a point where it will idle with the choke off. When it gets good and warm, it idles fine with the choke off. I've had the carb off, totally taken down, and cleaned every orifice within it. I've cleaned the pilot jet 2-3 times, and today installed a brand new pilot jet. To no avail, it still behaves the same, which absolutely ticks me off. Now reading this site it seems like this is a TTR problem, not just my problem. Has anyone out there found a solution to this problem? If so, and you can share it with us, I would appreciate it.