I HAD A K4 (1973) WHICH I BOUGHT IN 1978 AND HAD TILL 1982, ALTHOUGH MY MATES AT THE TIME HAD GT250´S AND YAMAHA 250´S WHICH ACCELARATED FASTER THE K4 COULD KEEP UP 80MPH ALL DAY WHILE THE 2 STROKES OVERHEATED AND WOULD HAVE TO CHANGE DOWN THROUGH THE GEARS AT THE SLIGHTEST HILL. I LOVED THAT BIKE, TOOK IT TO LONDON FROM SOUTH WALES SEVERAL TIMES. ANYONE SELLING ONE PLEASE CONTACT ME ON MY E MAIL