The China Railways YJ (Chinese: 跃进; pinyin: Yuè Jìn; lit. 'leap forward') design is based on China Railways PL2 class 2-6-2, itself derived from the JF62-8-2, the predecessor of the well known SY class mikado. According to Chinese sources a total of 202 locos were produced between 1958 and 1961.[1]
530 mm × 710 mm (20.866 in × 27.953 in) 482 mm × 660 mm (18.976 in × 25.984 in)(YJ 201-250) 500 mm × 710 mm (19.685 in × 27.953 in)(YJ 251-???) bore x stroke
Gibbons, Robin (2016). Locomotives of China - The JF6 Family - The JF6, PL2, YJ and SY Classes. United Kingdom: Tynedale Publishing. ISBN978-0-9934192-1-8.