TRX850, hmm where to start. Great motor, especially considering its from the early 80s and its agricultural origins which never changed much at all. You can boost it up 30hp with basic bolt on bits, but at the end of the day the rest of the bike will handle like a soggy pie. TRX forks, brakes, suspension & angles & C of G = sh1t.
Can't remember the guy who raced them in FX twins a few years back, he never won or anything, but I always thought his achievements were more a function of his ability than his bike, much like anything else I spose, but even more in this case!
It's a bike to romanticise, but please don't buy it
