Engine & Frame Numbers

On this page you will find Triumph, BSA, and Norton engine numbers along with frame serial numbers. Engine 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.

*When dating your motorcycle, do not go off of what the title says but instead your engine and frame numbers... Often times titles are not correct and do not reflect the "true" year. When ordering parts go off both your frame and engine numbers NOT the title 

Click here to download your free parts book for your Triumph, BSA or Norton motorcycle

Triumph 650 Unit Twins Engine & Frame Numbers (1963-1968)

Below you will find both Triumph engine and frame numbers for Triumph 650 unit twins from 1963-1968 and a Triumph 650 models list from 1963-1968.

Frame and engine numbers will be the same assuming they match as they would of when they left the factory. If your frame numbers or Triumph engine numbers do not match, you can still use this system to date each frame and / or the engine.

Triumph 650 Models (1963-1968)

 Engine & Frame Numbers (1963-1968)

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

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.  

Triumph 650 & 750 Engine & Frame Numbers (1969-1983)

Triumph 350 & 500 Unit Twins Engine & Frame Numbers (1957-1974)

Below you will find both Triumph engine and frame numbers for Triumph 350 and 500 unit twins from 1957-1974 and a Triumph models list from 1957-1974.

Frame and engine numbers will be the same assuming they match as they would of when they left the factory. If your frame numbers or Triumph engine numbers do not match, you can still use this system to date each frame and / or the engine.

Triumph 350 & 500 Models (1957-1974)

 Engine & Frame Numbers (1957-1969)

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.

Engine & Frame Numbers (1969-1974)

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

 Below you will find BSA engine and frame numbers for BSA 500 & 650 unit twins from 1962-1968. Frame and 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 prior to 1966 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.
 

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

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.  

BSA 250, 350, 441 & 500 Unit Singles Engine & Frame Numbers (1959-1973)

Below you will find BSA engine and frame numbers for all BSA unit singles produced from 1959-1973. Frame and engine numbers will be the same assuming they match as they would of when they left the factory.

Many early BSA unit singles prior to 1966 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.

BSA Unit Singles - Models (1959-1973)

 Engine & Frame Numbers (1959-1973)

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Norton Commando 750 & 850 Engine / Frame Numbers (1967-1975)

Below you will find Norton Commando 750 and 850 engine and frame numbers for all Norton twins produced from 1967-1975. Frame and engine numbers will be the same assuming they match as they would of when they left the factory.

If your frame or engine numbers do not match, you can still use this system to date each frame and / or engine.