the old dts were good,the 250s and 400s shared the same transmission more or less,these had reed valves whereas the spainish bikes didnt,,they take more skill to ride in feeling the engine and keeping it on the boil,,you cant be in the "wrong"too tall gear and just power out of it(like early honda elsinors had no reed valve)we always used pre mix and plugged the auto lubes,we just didnt trust them after a mate had one fail and lock up hes 400,i had a 73dt400b,and an it400 later on,plenty power,over powered,they look handsome aswell but really are just a road bike frame etc,short travel suspension,the early yz was no better,yammy got it all together in the mid 80s and by the early 90s the decline happened,the IT was a thinly disguised YZ untill the end,the IT became a 200 and was the best of the lot,a 250 kit made them a true super dirt bike,a mate had one from new and had it 250 kitted,it was #$%*ing fast man and light,,you could #$%* up on rough #$%* and it would forgive,they were great bikes and would still be very competitve now even against the new bikes!you can only engineer in so much handling to a point,,it cant get better and better and better,youd be building uncrashable bikes otherwise?