Bultaco 155 was created on the basis of Tralla 101, but it differed in a completely other ideology. Due to the powerful engine of a large volume, excellent reliability and the cheap price, it ideally suited the role of everyday bike. A motor carriage could be attached to model 155. The two-stroke engine had a volume of 153 cm3. Total 6,915pcs were produced from 1960 to 1962.