I remember reading a dirtwheels(a late 80's issue), the 86 tecate 3 and the quadzilla were the fastest at nearly 85 mph, 86 atc250r was at almost 80(trx was close). Really, the fastest atv ever produced in a tiger 500 three wheeler(limited number, usa built), dirtwheels had it to almost 90 and it still had more to go. They said that it had enough power pull 2 tooth bigger front sprocket too. Tiger didn't produce too much of them, as with the 80(lowest number), 125(very rare), 200(rare), 250(most common), and 500(very rare, few still around).
I don't know how these compare to the current atv's, atc250r's and tecate 3's are still blowing away current quads. I have to agree, top speed isn't too important. Get up and go is more important, I can't think of too many places except dunes and drag strips where you can open up atv's.
85/86 atc 250r, very modded, lrd 310pv, +1 lsr, shortrack kit, cr250r igntion, 39 pwk, paul turner hi-rev pipe, propeg nerf bars, HREATV custom frame,
86 atc200x- 84 250r exteneded axle, supertrapp pipe, 27mm carb, works rear shock, 84 250r front end(rebuilt w/ terry kit), 350x tripples, ported head, 12:1 piston, webcam,
crf450r quad, lsr frame, swinger, antifade, hyper beadlocks and the best of everything else.
88 trx 250r pced and reinforced frame, +3+0 t-pin, 310pv, cr ignition, 39 pwk, lsr rear end, elka shocks, aftermarket radiator, lrd pipe
06 ktm450exc, full skid plate/guards, radiator fan, clarke tank, dual sport kit, reg/ins/insp, steering stabilzer
98 200exc: street plated, skid/guards, dual sport lights, stabilizer and more.
07 ktm 250xc, skids, reg/ins, dampener, good lights
2011 atc450r in the works, suspension and details need to be worked out