OUR NUMBER FOR THIS BOOK IS PWBP01. BSA models from 1914 to 1923. 4¼ hp 1914 - 1920. 4¼ hp 1921 - 1923. 8 hp 1922 - 1923. 2¾ hp, 3½ hp & 6 hp - 1923. PERFECT FOR RESEARCHERS OF OLD PARTS AS ALL PARTS ARE PICTURED INDIVIDUALLY WITH A HUGE AMOUNT OF INTERESTING DATA.