I had a TRX250X a couple of years ago the engine had just been rebuilt on. All I can say is that bad boy was fast! I had fun on it and I'm 5'10" tall and at that time weighed 260 lbs.
I got it for next to nothing $350.00. I did put tires on it, wheel bearings, and tie rod ends. To make it a little nicer I did also put some new Maier plastic on it. That cost me more than my initial investment. After the work was done this little Quad was so much fun to ride, and handled like it was ready to hit the track.
I had no problems at all. Mine was the older moder that just had the kick-start. Even though some-tmes she would sit for weeks, with one or two swift kicks, she was off to the races. Always started fast, and ran even faster.
The dumbest thing I did was I sold. I did so because I had gone through a bunch of back surgeries and was afraid I would screw myself up riding it. But even though I have a Foreman now, I still miss my 250X.
The only bad thing about these little 4 wheelers is they have an issue with making the rider to go balls to the wall. Depending on your Son's age? You may have a hard time keeping him in check?
Just a super nice unit!