 1/4 mile in 14.8 seconds.The DS7 was the initial forerunner of the Yamaha RD series of motorcycles started in 1973.The major difference between the 250 cc DS7 and 350 cc R5 of 1972 and the 1973 RD250 and RD350 was that the DS7 and R5 utilized piston-port induction, whereas the RDs were introduced with reed valve induction.