a few other thoughts, one: your top speed is about right a true 90mph the previous 250b was quicker top end, but the 250DX had the most accurate speedo ever tested by motercycle news in the UK less than 2% out!, so who knows , your site actually gives a slower top end for the RD400DX which is nonsense the 400DX (C)) was good for about 105 or so, i read 112 on a steep hill once but 105mph is about right, if a 400 rider held of on the acceleration and kept the 250dx in his slipstream the 250dx could have pulled near to 100mph, i once "drafted" my friends 250dx behind my 400dx and enabled up both to blow off an rd350b much to the annoyance of its rider the RD250dx (C) had a tendency to blow pencil sized holes in the pistons this hapened to me twice and to several of my friends!! you list the 250dx as being 5speed it was actually 6speed, mine however had only 2 speeds, "flat out" or parked, a brilliant bike in every way what it lacked top end it made up mid range and carving the corners. i would love a ride on one again.