Engine & Frame Numbers

Engine & Frame Number Dating System
On this page you will find Triumph, BSA, and Norton engine and frame serial numbers. Engine serial numbers are usually located on the drive side of most British motorcycles below the cylinder barrel or above the primary cover on the engine case its self.
Frame numbers are usually stamped on the left side of the frame towards the top near the triple tree. Some BSA & Triumph models had frame numbers near the front engine support.     

 

Triumph 650 Unit Twins Engine & Frame Numbers 1963-1968

 

1970 Triumph Bonneville T120R

Below you will find Triumph engine numbers & frame numbers for 650 unit twins from 1963-1968. Frame & engine numbers will be the same assuming they match as they would of when they left the factory. If your frame or Triumph engine numbers do not match, you can still use this system to date each frame and / or the engine.

 

Year                                            Starting Number                        Ending Number

1963                                                    DU101                                           DU5824

1964                                                   DU5825                                          DU13374

1965                                                   DU13375                                        DU24874

1966                                                   DU24875                                        DU44393

1967                                                   DU66246                                        DU66245

1968                                                   DU66246                                        DU85903

1969                                                   DU85904                                        DU90282

 

 

Triumph 650 & 750 Unit Twins Engine & Frame Numbers 1969-1983

 Triumph T140 750 Bonneville

 

In 1969, Triumph added a two-letter prefix to the actual engine number in order to indicate the month and model year - but not the actual year of manufacture. In 1981 when the coding system would have been repeated, a third letter (A) was added to distinguish the number from the previous years.  

 

Example T120R ED56946. E (Month) = May / D (Year) = 1970

 

 First letter = month of manufacture            Second letter = model year of manufacture

A                            January                          C                                              1969

B                            February                        D                                              1970  

C                            March                            E                                              1971

D                             April                             G                                              1972

E                             May                              H                                              1973 

G                            June                              J                                               1974

H                             July                              K                                               1975

J                             August                           N                                               1976

K                            September                     P                                                1977

N                           October                           X                                               1978

P                            November                      A                                               1979

X                            December                      B                                                1980

                                                                  DA                                              1981

                                                                  DA                                              1982

                                                                  EA                                               1983

 

 

BSA 500 & 650 Unit Twins Engine & Frame Numbers 1962-68

 

1966 BSA A65 650 Lightning

 Below you will find BSA engine & frame numbers for BSA 500 & 650 unit twins from 1962-1968. Frame & engine numbers will be the same assuming they match as they would of when they left the factory.

Many early BSA A50 & A65 unit twins left the factory without matching engine and frame numbers. If your frame or engine numbers do not match, you can still use this system to date each frame and / or engine. A50 = 500CC A65 = 650CC.

 

 

 

Year / Model                                     Engine Number                    Frame Number

1962 A50 Star Twin (Cable Rear Brake)          A50-101                        A50-101

1962 A50 Star Twin (Rod Rear Brake)           A50-101                        A50A-101

1962 A65 Star Twin (Cable Rear Brake)         A65-101                         A50-101

1962 A65 Star Twin (Rod Rear Brake)             A65-101                        A50A-101

1963 A50 Star Twin (Rod Rear Brake)            A50-823                         A50-2288

1963 A65 Star Twin (Rod Rear Brake)            A65-1947                        A65-2288

1964 A50 Star                                                 A50A-101                        A50-5501

1964 A50 Police                                             A50AP-101                     A50-5501

1964 A50C Cyclone                                        A50B-101                        A50B-101

1964 A65 Star                                                 A65A-101                         A50-5501

1964 A65 Police                                             A65AP-101                      A50-5501

1964 A65R Rocket                                          A65B-101                         A50B-101

1964 A65T Thunderbolt Rocket                      A65B-101                         A50-5501

1964 A65R Rocket W/ rev Counter                 A65C-101                         A50-5501

1964 A65L Lightning Rocket                           A65D-101                         A50B-101

1964 A65SH Spitfite Hornet                            A65E-101                          A50B-101

1965 A50 Star                                                  A50A-686                          A50-8437

1965 A50 Police                                              A50AP-121                       A50-8437

1965 A50 Cyclone Competition UK                 A50DC-101                       A50-4001

1965 Cyclone UK                                            A50DC-101                       A50-4001

1965 A50C Cyclone Road Model                    A50D-101                         A50B-4001

1965 A50CC Cyclone Competition                  A50B-507                         A50-4001

1965 A65 Star                                                 A65A-1134                        A50-8437

1965 A65 Police                                             A65AP-267                        A50-8437

1965 A65 Lightning                                        A65DC-2158                    A50B-4001

1965 A65 Lighting Clubman                           A65DC-2158                    A50B-4001

1965 A65L Lightning Rocket                           A65D-1742                      A50B-4001

1965 A65R Rocket                                           A65B-334                        A50-8437

1965 A65R Rocket W/ Rev Counter                A65C-1082                       A50-8437

1965 A65SH Spitfire Hornet                            A65E-701                         A50B-4001

1966 A50R Royal Star                                     A50R-101                       A50C-101

1966 A50W Wasp                                            A50W-101                      A50C-101

1966 A65T Thunderbolt                                  A65T-101                        A50C-101

1966 A65L Lightning                                       A65L-101                       A50C-101

1966 A65LC Lightning Clubman                    A65LC-101                      A50C-101

1966 A65S Spitfire MK II                                A65S-101                        A50C-101

1966 A65H Hornet                                          A65H-101                        A50C-101

1967 A50R Royal Star                                    A50RA-101                     A50RA-101

1967 A50W Wasp                                           A50WA-101                    A50WA-101

1967 A65T Thunderbolt                                  A65TA-101                     A65TA-101

1967 A65L Lightning                                      A65LA-101                     A65LA-101

1967 A65SA Spitfire MK III                             A65SA-101                     A65SA-101

1967 A65H Hornet                                          A65HA-101                     A65HA-101

1968 A50R Royal Star                                    A50RB-101                     A50RB-101

1968 A50W Wasp                                           A50WB-101                    A50WB-101

1968 A65T Thunderbolt                                 A65TB-101                      A65TB-101

1968 A65L Lightning                                     A65LB-101                      A65LB-101

1968 A65F Firebird Scrambler                      A65FB-101                      A65FB-101

1968 A65S Spitfire MKIV                               A65SB-101                      A65SB-101

 

 

BSA 500 & 650 Unit Twins Engine & Frame Numbers 1969-1972

 

BSA Motorcycle Advertisment 1968

 

In 1969, BSA (exactly like Triumph) added a two-letter prefix to the actual engine number in order to indicate the month and model year. But, not the actual year of manufacture.  

 

Example A65 Lightning BC56946. B (Month) = February / C (Year) = 1969

 

 First letter = month of manufacture           Second letter = model year of manufacture

A                            January                          C                                              1969

B                            February                        D                                              1970  

C                            March                             E                                              1971

D                             April                              G                                              1972

E                             May                             

G                            June                            

H                             July                            

J                             August                        

K                            September                 

N                           October                        

P                            November                   

X                            December