i am going to buy a new 250ex and i just ride trails atv is for my son but we just ride trails does any one know any kind of accesories i would want to put on it or just leave plain

 

They are really good machines stock. Maybe a 6-pack rack, make him carry your lunch! I always recommend nerf bars for a sport machine, maybe even heel guards depending on the setup. Possibly some aftermarket skids to keep the rear diff and engine better protected. A tire swap may be in order depending on terrain and riding style, although I would put some hours on the stockers first.

 

They are a great bike for trail riding right off the showroom floor, but all of scooter's suggestions are good ideas. Nerf bars are always a great investment, it'll keep your son from running over his ankles if his feet slide off a wet/muddy footpeg. Frames and rear differentials can be very expensive to repair and replace, so i'd recommend a full set of aluminum skid plates (chassis, a-arms, and swingarm), and a wider front bumper to protect those a-arms. The stock tires aren't too bad for trail riding, but make sure you buy and take along a tire plug kit and co2 tire inflator. The stock tires are only 2-plys, and puncture fairly easily.