we had 23 of them at our shop when i did atv tours out here in vegas, they do take a beating, bars bend easy. and in the summer since it is an air cooled 2 stroke, they can tend to over heat and blow the motors. all you have to do is get the right air filter, clean it all the time, and run it a bit rich and carry extra plugs.
up grades for the TB 250 are pretty simple, new clutch spring, pipe. you can get the whole package for about 500.00 and it really wakes up the 250. also, these pigs are heavy as hell! its dam near a 2 man lift to get it in and out of a truck.