Abridged version. Working on a bike my brother picked up. TTR250. Gone through the carb several times. Its clean as a pin. It will crank but runs terribly rich. Black smoke barely idles, bogs when you give it throttle. Stock jets. Runs the same even with the airbox completely off, adjusting fuel screw makes little difference. I have not tried a different carb as they are hard to find and not wanting to put a bunch of money in it. I have not check the timing yet but that is the next thing unless i find a cheap used carb online I read these are prone to jump time. Question: if the bike has jumped a tooth on the timing gear would it illustrate this symptom where it runs but is firing at the wrong time and all the unburnt fuel is just hanging around in the cylinder ??
