Engine and frame numbers
1930
The BSA numbering system has changed quite a few times over the years. As of 1930 a prefix was introduced which referred to the model year. In 1930 the prefix consisted of 2 letters (the first being the year letter), which was reduced to one from 1931 – 1936 (only the year letter). In 1937 the system was changed again. As of model year 1937 the frame used by a group of models got the prefix from the first model in that group for that year e.g. HM19 indicated a 1937 M group model. Please note that a model year started in September prior to the calendar year and ended in August that same calendar year. E.g. the model year 1936 started in September 1935 and ended in August 1936. These prefixes were often also stamped on parts for the motorcycles for that production year above the Piled Arms stamp. There is no logic in the sequence as you can see from the table below.| Model | Type | Engine number | Frame number | Remarks |
|---|---|---|---|---|
| A30-2 | 1.74 h.p. | Y… | E… | two stroke |
| B30-3 | 2.49 h.p. S.V | XM.101 | XB.101 | |
| B30-4 | 2.49 h.p. O.H.V. | XR.101 | XB.101 | |
| L30-5 | 3.49 h.p. S.V. | XT.101 | XB.101 | |
| L30-5 | 3.49 h.p. S.V. commercial | XT.101 | XA.101 | Commercial |
| S30-7 | 4.93 h.p. S.V. | XS.101 | XH.101 | Sloper |
| H30-8 | 5.57 h.p. S.V. | XX.101 | XH.101 | Sloper |
| S30-9 | 4.93 h.p. De Luxe S.V. | XX.101 | XH.101 | Sloper |
| H30-10 | 5.57 h.p. S.V. De luxe | XX.101 | XH.101 | Sloper |
| L30-11 | 3.49 h.p. O.H.V | XS.101 | XH.101 | Sloper |
| S30-12 | 4.93 h.p. O.H.V. | XW.101 | XX.101 | Sloper |
| S30-13 | 4.93 h.p. O.H.V. De Luxe | XP.101 | XH.101 | Sloper |
| E30-14 | 7.70 h.p. S.V. V-Twin | XY.101 | XD.101 | V-twin |
| G30-15 | 9.86 h.p. S.V. V-Twin | XY.101 | XD.101 | V-twin |
| G30-16 | 9.86 h.p. W.T. S.V. V-Twin | XZ.101 | XG.101 | V-twin |
| S30-18 | 4.93 h.p. Light S.V. | XU.101 | XL.101 | |
| S30-19 | 4.93 h.p. O.H.V. Light | XU.101 XO.101 | XL.101 |
1931
| Model | Type | Engine number | Frame number | Remarks |
|---|---|---|---|---|
| B31-1 | 2.49 h.p. S.V. | Y1.101 | Y1.101 | |
| B31-2 | 2.49 h.p. O.H.V. | Y2.101 | Y1.101 | |
| B31-3 | 2.49 h.p. O.H.V. de Luxe | Y3.101 | Y3.101 | |
| L31-4 | 3.49 h.p. S.V. | Y4.101 | Y1.101 | |
| L31-5 | 3.49 h.p. S.V. de Luxe | Y5.101 | Y5.101 | |
| L31-6 | 3.49 h.p. O.H.V. | Y6.101 | Y5.101 | |
| S31-7 | 3.49 h.p. S.V. | Y7.101 | Y7.101 | Sloper |
| H31-8 | 5.57 h.p. S.V. | Y8.101 | Y7.101 | Sloper |
| S31-9 | 4.93 h.p. O.H.V. | Y9.101 | Y7.101 | |
| S31-10 | 4.93 h.p. O.H.V. de Luxe | Y10.101 | Y7.101 | Sloper |
| E31-11 | 7.70 h.p. S.V. | Y11.101 | Y11.101 | 2 gallon tank V-Twin |
| E31-11 | 7.70 h.p. S.V. | Y11.101 | Y11A.101 | 3 gallon tank V-Twin |
| G31-12 | 9.86 h.p. S.V. W.T. | Y12.101 | Y12.101 | V-Twin World Tour |
1932
| Model | Type | Engine number | Frame number | Remarks |
|---|---|---|---|---|
| B32-1 | 2.49 h.p. O.H.V. | Z1.101 | Z1.101 | |
| B32-2 | 3.49 h.p. S.V. | Z2.101 | Z1.101 | |
| L32-3 | 3.49 h.p. O.H.V. Special | Z3.101 | Z3.101 | |
| L32-4 | 3.49 h.p. S.V. de Luxe | Z4.101 | Z4.101 | hand gear change |
| L32-4 | 3.49 h.p. S.V. de Luxe | Z4.101 | Z5.101 | foot gear change |
| L32-5 | 3.49 h.p. O.H.V. de Luxe | Z5.101 | Z4.101 | hand gear change |
| L32-5 | 3.49 h.p. O.H.V. de Luxe | Z5.101 | Z5.101 | foot gear change |
| L32-5 | 3.49 h.p. O.H.V. Blue Star | Z5.101 Z11.1051* | Z4.101 | hand gear change |
| L32-5 | 3.49 h.p. O.H.V. Blue Star | Z5.101 Z11.1051 | Z5.101 | foot gear change |
| W32-6 | 4.99 h.p. S.V. | Z6.101 | Z6.101 | hand gear change |
| W32-6 | 4.99 h.p. S.V. | Z6.101 | Z7.101 | foot gear change |
| W32-7 | 4.99 h.p. O.H.V. | Z7.101 | Z6.101 | hand gear change |
| W32-7 | 4.99 h.p. O.H.V. | Z7.101 | Z7.101 | foot gear change |
| W32-7 | 4.99 h.p. O.H.V. Blue Star | Z7.101 Z12.463 | Z6.101 | hand gear change |
| W32-7 | 4.99 h.p. O.H.V. Blue Star | Z7.101 Z12.463** | Z7.101 | foot gear change |
| S32-8 | 4.93 h.p. O.H.V. de Luxe | Z8.101 | Z8.101 | Sloper |
| H32-9 | 5.57 h.p. S.V. de Luxe | Z9.101 | Z8.101 | Sloper |
| G32-10 | 9.86 h.p. S.V. | Z10.101 | Z10.101 | V-Twin |
* Prefix Z5 up to engine number Z5.1050 after that prefix Z11
** Prefix Z7 up to engine number Z5.462 after that prefix Z12
1933
| Model | Type | Engine number | Frame number | Remarks |
|---|---|---|---|---|
| X33-0 | 1.49 h.p. O.H.V. | A150-101 | A150-101 | Only made for the Italian market |
| B33-1 | 2.49 h.p. S.V. | A1-101 | A1-101 | |
| B33-2 | 2.49 h.p. O.H.V. S.P. | A2-101 | A1-101 | |
| B33-3 | 2.49 h.p.O.H.V. Blue Star Junior | A3-101 | A3L-101 | |
| R33-4 | 3.48 h.p. O.H.V. | A4-101 | A4-101 | |
| R33-5 | 3.48 h.p. O.H.V. Blue Star | A5-101 | A4-101 | hand gear change |
| R33-5 | 3.48 h.p. O.H.V. Blue Star | A5-101 | A5-101 | foot gear change |
| W33-6 | 4.99 h.p. S.V. | A6-101 | A4-101 | |
| W33-7 | 4.99 h.p. O.H.V. | A7-101 | A4-101 | |
| W33-8 | 4.99 h.p. O.H.V. Blue Star | A8-101 | A4-101 | hand gear change |
| W33-8 | 4.99 h.p. O.H.V. Blue Star | A8-101 | A5-101 | foot gear change |
| W33-9 | 4.99 h.p. O.H.V. Special | A9-101 | A9R-101 | hand gear change |
| W33-9 | 4.99 h.p. O.H.V. Special | A9-101 | A9L-101 | foot gear change |
| M33-10 | 5.95 h.p. S.V. de Luxe | A10-101 | A10-101 | Sloper |
| M33-11 | 5.95 h.p. O.H.V. de Luxe | A11-101 | A10-101 | Sloper |
| G33-12 | 9.86 h.p. S.V. Light | A12-101 | A12-101 | V-Twin |
| G33-13 | 9.86 h.p. S.V. W.T. | A13-101 | A13-101 | V-Twin World Tour uitvoering |
| J33-14 | 4.98 h.p. O.H.V. War Office Twin | A14-101 | A14-101 | War Office V twin |
1934
| Model | Type | Engine number | Frame number | Remarks |
|---|---|---|---|---|
| X34-0 | 1.49 h.p. O.H.V. | B150-101 | B1-101 | |
| B34-1 | 2.49 h.p. S.V. | B1-101 | B1-101 | |
| B34-2 | 2.49 h.p. O.H.V. | B2-101 | B1-101 | |
| B34-3 | 2.49 h.p. O.H.V. Blue Star | B3-101 | B3-101 | |
| R34-4 | 3.48 h.p. O.H.V. | B4-101 | B4-101 | |
| R34-5 | 3.48 h.p. O.H.V. Blue Star | B5-101 | B4-101 | |
| R34-6 | 3.48 h.p. O.H.V. Special | B6-101 | B6-101 | |
| W34-7 | 4.99 h.p. S.V. | B7-101 | B7-101 | |
| W34-8 | 4.99 h.p. O.H.V. | B8-101 | B4-101 | |
| W34-9 | 4.99 h.p. O.H.V. Blue Star | B9-101 | B4-101 | |
| W34-10 | 4.99 h.p. O.H.V. Special | B10-101 | B6-101 | |
| J34-11 | 4.98 h.p. O.H.V. Twin | B11-101 | B11-101 | V-Twin |
| M34-12 | 5.95 h.p. S.V. de Luxe | B12-101 | B12-101 | Sloper |
| M34-13 | 5.95 h.p. O.H.V. de Luxe | B13-101 | B12-101 | |
| G34-14 | 9.86 h.p. S.V. W.T. | B14-101 | B14-101 | V-Twin |
| J34-15 | 4.98 h.p. O.H.V. War Office Twin | B15-101 | B15-101 | War Office V-twin |
| W34-16 | 4.99 h.p. O.H.V. Fluid Flywheel | B16-101 | B16-101 | Fluid Flywheel |
| B34-17 | 2.49 h.p. O.H.V. Sports | B17-101 | B3-101 |
1935
| Model | Type | Engine number | Frame number | Remarks |
|---|---|---|---|---|
| X35-0 | 1.49 h.p. O.H.V. | E0-101 | E1-101 | |
| B35-1 | 2.49 h.p. S.V. | E1-101 | E1-101 | |
| B35-2 | 2.49 h.p. O.H.V. | E2-101 | E1-101 | |
| B35-3 | 2.49 h.p. O.H.V. de Luxe | E3-101 | E3-101 | |
| R35-4 | 3.48 h.p. O.H.V. de Luxe | E4-101 | E3-101 | |
| R35-5 | 3.48 h.p. O.H.V. Blue Star | E5-101 | E5-101 | |
| R35-17 | 3.48 h.p. Twin Port | E5-101 | E17-101 | |
| W35-6 | 4.99 h.p. S.V. | E6-101 | E6-101 | |
| W35-7 | 4.99 h.p. O.H.V. | E7-101 | E5-101 | |
| W35-8 | 4.99 h.p. O.H.V. Blue Star | E8-101 | E5-101 | |
| W35-9 | 4.99 h.p. O.H.V. Special | E9-101 | E9-101 | |
| M35-10 | 5.95 h.p. S.V. | E10-101 | E10-101 | Sloper |
| M35-11 | 5.95 h.p. O.H.V. | E11-101 | E10-101 | Sloper |
| J35-12 | 4.98 h.p. O.H.V. Twin | E12-101 | E12-101 | V-Twin |
| G35-14 | 9.86 h.p. S.V. | E14-101 | E14-101 | V-Twin |
| J35-15 | 4.98 h.p. O.H.V. War Office Twin | E15-101 | E15-101 | War Office V-Twin |
1936
| Model | Type | Engine number | Frame number | Remarks |
|---|---|---|---|---|
| X-0 | 1.49 h.p. O.H.V. | D0-101 | D1-101 | |
| B-1 | 2.49 h.p. S.V. | D1-101 | D-101 | |
| B-2 | 2.49 h.p. O.H.V. | D2-101 | D1-101 | |
| B-18 | 2.49 h.p. O.H.V. Light de Luxe | D18-101 | D1-101 | |
| B-3 | 2.49 h.p. O.H.V. de Luxe | D3-101 | D3-101 | |
| R-4 | 3.48 h.p. O.H.V. de Luxe | D4-101 | D3-101 | |
| R-19 | 3.48 h.p. O.H.V. Competition | D19-101 | D3-101 | |
| R17 | 3.48 h.p. O.H.V. S.P. | D17-101 | D6-101 | |
| W-6 | 4.99 h.p. S.V. | D6-101 | D6-101 | |
| Q-7 | 4.96 h.p. O.H.V. | D7-101 | D6-101 | |
| Q-8 | 4.96 h.p. O.H.V. Empire Star | D8-101 | D8-101 | |
| R-5 | 3.48 h.p. O.H.V. Empire Star | D5-101 | D8-101 | |
| Q-8 | 4.96 h.p. O.H.V. Empire Star | 3D8-101 | D38-1101 | mid season change |
| R-5 | 3.48 h.p. O.H.V. Empire Star | 3D5-101 | D38-1101 | mid season change |
| J-12 | 4.98 h.p. O.H.V. Twin | D12-101 | D12-101 | V-Twin |
| M-10 | 5.95 h.p. S.V. | D10-101 | D10-101 | |
| Y-13 | 7.48 h.p. O.H.V. | D13-101 | D13-101 | V-Twin |
| G-14 | 9.86 h.p. S.V. | D14-101 | D14-101 | V-Twin |
| R-20 | 3.48 h.p. O.H.V. New Blue Star | D20-101 | D6-101 | |
| Q-21 | 4.96 h.p. O.H.V. New Blue Star | D21-101 | D6-101 |
1937
| Model | Type | Engine number | Frame number | Remarks |
|---|---|---|---|---|
| B20 | 250 c.c. S.V. Tourer | HB20-101 | HB20-101 | |
| B21 | 250 c.c. O.H.V. Sports | HB21-101 | HB20-101 | |
| B22 | 250 c.c. O.H.V. Empire Star | HB22-101 | HB20-101 | |
| B23 | 350 c.c. S.V. Tourer | HB23-101 | HB20-101 | |
| B24 | 350 c.c. O.H.V. Empire Star | HB24-101 | HB24-101 | |
| B25 | 350 c.c. O.H.V. Competition | HB25-101 | HB24-101 | |
| B26 | 350 c.c. O.H.V. Sports | HB26-101 | HB24-101 | |
| M19 | 350 c.c. O.H.V. de Luxe | HM19-101 | HM19-101 | |
| M20 | 500 c.c. S.V.Tourer | HM20-101 | HM19-101 | |
| M21 | 600 c.c. S.V. Tourer | HM21-101 | HM19-101 | |
| M22 | 500 c.c. O.H.V. Sports | HM22-101 | HM19-101 | |
| M23 | 500 c.c. O.H.V. Empire Star | HM23-101 | HM19-101 | |
| Y13 | 750 c.c. O.H.V. Vee Twin | HY13-101 | HY13-101 | V-Twin |
| G14 | 1000 c.c. S.V. Vee Twin | HG14-101 | HG14-101 | V-Twin |
1938
| Model | Type | Engine number | Frame number | Remarks |
|---|---|---|---|---|
| B20 | 250 c.c. S.V. Tourer | JB20-101 | JB20-101 | |
| C10 | 250 c.c. S.V. | JC10-101 | JC10-101 | |
| B21 | 250 c.c. O.H.V. Sports | JB21-101 | JB20-101 | |
| B22 | 250 c.c. O.H.V. Empire Star | JB22-101 | JB20-101 | |
| B23 | 350 c.c. S.V. Tourer | JB23-101 | JB20-101 | |
| B24 | 350 c.c. O.H.V. Empire Star | JB24-101 | JB24-101 | |
| B25 | 350 c.c. O.H.V. Competition | JB25-101 | JB24-101 | |
| B26 | 350 c.c. O.H.V. Sports | JB26-101 | JB24-101 | |
| M19 | 350 c.c. O.H.V. de Luxe | JM19-101 | JM19-101 | |
| M20 | 500 c.c. S.V. Tourer | JM20-101 | JM19-101 | |
| M21 | 600 c.c. S.V. Tourer | JM21-101 | JM19-101 | |
| M22 | 500 c.c. O.H.V. Sports | JM22-101 | JM19-101 | |
| M23 | 500 c.c. O.H.V. Empire Star | JM23-101 | JM19-101 | |
| M24 | 500 c.c. O.H.V. Gold Star | JM24-101 | JM24-101 | first Gold Star |
| Y13 | 750 c.c. O.H.V. Vee Twin | JY13-101 | JY13-101 | V-Twin |
| G14 | 1000 c.c. S.V. Vee Twin | JG14-101 | JG14-101 | V-Twin |
1939
| Model | Type | Engine number | Frame number | Remarks |
|---|---|---|---|---|
| C10 | 250 c.c. S.V. Standard | KJC10- | KJC10- | 1938 production |
| C10 | 250 c.c. S.V. De Luxe | KC10-101 | KC10-101 | |
| C11 | 250 c.c. O.H.V. | KC11-101 | KC10-101 | |
| B21 | 250 c.c. O.H.V. Standard | KJB21- | KJB20- | 1938 production |
| B21 | 250 c.c. O.H.V. De Luxe | KB21-101 | KB21-101 | |
| B23 | 350 c.c. S.V. Standard | KJB23- | KJB20- | 1938 production |
| B23 | 350 c.c. S.V. De Luxe | KB23-101 | KB21-101 | |
| B24 | 350 c.c. O.H.V. Silver Star | KB24-101 | KB24-101 | |
| B25 | 350 c.c. O.H.V. Competition | KB25-101 | KB24-101 | |
| B26 | 350 c.c. O.H.V. | KB26-101 | KB24-101 | |
| M20 | 500 c.c. S.V. Standard | KMS20-101 | KM20-101 | |
| M20 | 500 c.c. S.V. De Luxe | KM20-101 | KM20-101 | |
| M21 | 600 c.c. S.V. | KM21-101 | KM20-101 | |
| M22 | 500 c.c. O.H.V. Standard | KJM22- | KJM19- | 1938 production |
| M22 | 500 c.c O.H.V. De Luxe | KM22-101 | KM20-101 | |
| M23 | 500 c.c. O.H.V. Silver Star | KM23-101 | KM23-101 | |
| M24 | 500 c.c. O.H.V. Gold Star | KM24-101 | KM24-101 | |
| G14 | 1000 c.c. S.V. Vee Twin | KG14-101 | KG14-101 | V-Twin |
1940
| Model | Type | Engine number | Frame number | Remarks |
|---|---|---|---|---|
| C10 | 250 c.c. S.V. | WC10-101 | WC10-101 | |
| C11 | 250 c.c. O.H.V. | WC11-101 | WC10-101 | |
| C12 | 350 c.c. S.V. | WC12-101 | WC10-101 | |
| B29 | 350 c.c. O.H.V. Silver Sports | WB29-101 | WB29-101 | |
| M20 | 500 c.c. S.V. | WM20-101 | WM20-101 | |
| M21 | 600 c.c. S.V. | WM21-101 | WM20-101 | |
| M23 | 500 c.c. O.H.V. Silver Star | WM23-101 | WM20-101 | |
| G14 | 1000 c.c. S.V. Vee Twin | WG14-101 | WG14-101 | V-Twin |