Checking the engine and frame numbers should be the first step in taking on any bike project.  This allows one to determine the year of the machine being serviced. This also ensures you get the correct parts if you are ordering by description alone. The condition of the number may also give indication if it has been tampered with.

We have listed the more common engine numbers at the top of the page. Further down we have a more comprehensive list.

TRIUMPH TWINS
1937 to 1949
The year and model were used as a prefix to the engine number
From 1937 to 1939 the final digit ( 7, 8 or 9 ) was used.

From 1946 to 1949 the final two figures ( 46, 47, 48 or 49.)

The model numbers were T or 5T for the Speed Twin, T100 for Tiger 100, 3T for 350 twin & TR5 for Trophy.

Typical numbers were thus:
8-T-1234 ( 1938 Speed Twin )
47-5T-23456 ( 1947 Speed Twin )
9-T100-45678 ( 1939 Tiger 100 )

Pre-war frames ( 1937 / 39 ) used the prefix TH for the 500cc models ( 5T & T90 ) and TF for the Tiger 100.

Engine numbers commenced at:
1946 – 72000
1947 – 79046
1948 – 88782
1949 – 100762

1950 to 1962 Pre-Unit 500 & 650cc
Engine numbers had a prefix indicating the model type along the lines above such as 3T, 5T, 6T, T100, T110, 3TA, 5TA etc. This was followed by a number from the list below.

YEAR – Pre-Unit 500 & 650cc

1950 – From 100N
1951 – 101NA to 15808NA
1952 – 15809NA to 25000NA then 25000 to 32302
1953 – 32303 to 44134
1954 – 44135 to 56699
1955 – 56700 to 70929
1956 – 70930 to 82799 then 0100 to 0944
1957 – 0945 to 011115
1958 – 011116 to 020075
1959 – 020076 to 029363
1960 – 029364 to 030424 then D101 to D7726
1961 – D7727 to D15788
1962 – D15789 on

1963 to 1968 Unit 650cc

1963 – DU101 to DU5824
1964 – DU5825 to DU13374
1965 – DU13375 to DU24874
1966 – DU24875 to DU44393
1967 – DU44394 to DU66245
1968 – DU66246 to DU90282

1957 to 1968 Unit 350 & 500cc

1957 – H101 to H760
1958 – H761 to H5484
1959 – H5485 to H11511
1960 – H11512 to H18611
1961 – H18612 to H25251
1962 – H25252 to H29732
1963 – H29733 to H32464
1964 – H32465 to H35986
1965 – H35987 to H40527
1966 – H40528 to H49832
1967 – H49833 to H57082
1968 – H57083 to H67331
Frame number prefix :

Rigid – 3T = TC
Rigid – 5T, T100, 6T, TR5 = TF
Swing Arm – all pre-unit = S
Swing Arm – ’21’ = H

1969 onwards
Note: The engine number is located on the left side of the engine immediately below the cylinder barrel flange. The number is stamped onto the raised pad.
The frame number is stamped on the left side of the frame, on the front engine mounting lug.

The first letter indicates the month of manufacture as follows:-

A – January
B – February
C – March
D – April
E – May
G – June
H – July
J – August
K – September
N – October
P – November
X – December

The second letter indicates the season year of manufacture as follows :-

C – 1969
D – 1970
E – 1971
G – 1972
H – 1973
J – 1974
K – 1975
N – 1976
P – 1977
X – 1978
A – 1979
B – 1980

The third section is a numerical block of five figures which commence with engine number 00100.
The fourth section indicates the model.

Example: NC00100T120R – N=Month C=Year, Number, T120R=Model.

 

NORTON YEAR AND MODEL CODES 1946-1975

Code Year
A 1946
B 1947
C 1948
D 1949
E 1950
F 1951
G 1952
H 1953
J 1954
K 1955
L 1956
M 1957
N 1958
P 1959
R 1960

Norton Model Codes
Code Model
2 16H
3 18
3T 500T
4 ES2
6 19R
7 Big 4
8 16H or Big Four Plunger
9 19S
10 International 40
10M Manx 40
10M2 Manx 40 Featherbed
11 International 30
11M Manx 30
11M2 Manx 30 Featherbed
12 Model 7
122 88
13 50
14 99
15 77 & Nomad
16 Nomad
17 Jubilee
18 All 650cc Twins
19 Navigator
20 Atlas
20M3 Commando (Distributor)
20M3S Commando (Camshaft Pionts)
50 AMC 50
ES Electra
ES2 AMC ES2
D De-Luxe Twin
SS Sports Special Twin
Q Quietening Ramp Cams

Norton Serial Numbers
Year Number
1945 1001
1946 2131
1947 7756
1948 13792
1949 20701
1950 27100
1951 35560
1952 42700
1953 48900
1954 55350
1955 60700
1956 66600
1957 71360
1958 77400
1959 80488
1960 87038
1961 94500
1962 101060
1963 105000
1964 108000
1965 111650
1966 115870
1967 119760
1968 124300
1969 130000
1970 134700
1971 141700
1972 200001
1973 212278
1973 300000 (850)
1974 307311
1975 325000 (MK3)
125001 (Frame)

Norton 750 Twins Numbers
750cc Twins
1963 From 104001
1964 From 108000
1965-68 From 114870
1969-70 From 138973
1971 From 142151
1972 From 200004
1973-74 From 301000
1975 From 330000

 

BSA ENGINE AND FRAME NUMBERS

On most BSA’s the frame number is located in the following places. It is always stamped; raised numbers are casting part numbers. Up until 1968 it is rare for the engine and frame number to be identical and where the frame is shared by several models the codes start with the smallest model e.g. all A series models have A7 or A50 prefixes with the exception of the Rocket Gold Star and Super Flash.

Pre-war Motorcycles.

This varies from model to model but usually it is on the front top frame member either by the front seat stay or by the steering head.

1950’s

On the front down tube below or in front of the petrol tank. The exception is the early Bantams where the frame number is between the front engine mounting plate. These are usually faint and small.

1960-65

By the steering head reinforcing plate or front down tube. Some Bantams on the engine mounting plate, these sometimes break and re-welding obliterates the stamping.

1965-1968

Usually on the front engine mounting lug.

1968 onward

Front engine mounting lug but the engine and frame numbers are the same.

1971 oil in frame models

Steering head stem. The oil in frame B-series are stamped on the prop stand bracket.

Engine markings

Engine numbers are easier to find usually by the crankcase mouth on the primary side. Exceptions are the Bantams which could be stamped on the front mounting point or just behind the crankcase mouth.

This is just a guide and will fit most situations but frames were legitimately re-stamped by dealers if the original was damaged and a replacement fitted. These could be stamped anywhere and often were not stamped at all!

Identifying engine and frame numbers, 1969 season onward

Owners with late model BSA’s can easily identify the month and year of their machine as the factory adopted a dating system for frame and engine numbers for the 1969 season models. As with all previous BSA seasons the model year started after the factory shutdown in July so that 1969 models were those made from August 1968, through to July 1969. They would however have some machines in stock so that so that it is possible that a July model may be to either the previous or the next year’s specification.

The code consisted of three parts, the first as two letters giving month and year respectively, the second was a five digit number and the third a model code. The engine and frame received the same markings.

The date letters are as follows:

1St  Letter    2nd Letter

A – January    C – 1969 Model

B – February    D – 1970 Model

C – March    E – 1970 Model

D – April     G – 1972 Model

E – May     H – 1973 Model

G – June     J – 1974 Model

H – July  

J – August    To avoid confusion

K – September    ‘F’, ‘I’, ‘O’, and ‘L’ were

N – October    not used, although it is  

P – November    is to confuse letters ‘C’

X – December    and ‘G’.

The model designations are as follows. The years given are all model years:

A Series
Rocket Three – A75R –through all years.
Rocket Three five speed – A75RV, 1969 and 1970.
A75V – 1971 and 1972.
Royal Star A50R – through to 1970.
Thunderbolt A65T – through all years.
Police Special A65P – through all years.
Lightning A65L – through all years.
Firebird A65F – 1969 and 1970.
A65FS – 1971.

Lightning 750 A70L 1972.
Note in 1972 the frames for the twins were marked A65 with no model designation, from XG.00101.A65 on.

B Series
This is a bit complicated!
Starfire B25S – Sept 1968 to 1970.
Gold Star 250 – B25SS 1971.
Victor 250 – B25T 1971.
Fleetstar – B25FS through to 1971
Victor Special B44VS 1969 (C) November 1968 through June 1969 then 1970 (D) July 1969  to July 1970
Shooting Star B44SS 1969 (C) November 1968 through August 1969 then 1970 (D) July 1969 through July 1970
Gold Star 500 B50SS 1971 to 1972
Victor 500 B50T 1971 to 1972
Victor MX B50MX 1971 to 1973

BSA
250cc B25, C25
1967 From C25-101
1968 From B25-101
1969 From KC06301-B25S
1970 From JD00101-B25S
1971 From JE00101-B25SS

441cc B44 Victor Special
1966 B44E-101
1967 B44EA-101
1968 B44B-101
1969 PC07723-B44VS
1970 HD00101-B44VS

441cc B44 Shooting Star
1967 B44R-101
1968 B44B-101
1969 PC07793-B44SS
1970 JC00101-B44SS

500cc B50 All Models
1971 JE00101
1972 JG00101
1973 Not Published

500cc & 650cc A50 & A65
1962-65 Not Published
1966 A50/A65 * 101
1967 A50/A65 * A101
1968 A50/A65 * B101
1969 A50/A65 * C101
1970 A50/A65 * HD00101
1971 A65 * JE00101
1972 A65 * JG00101
* Insert model letter of motorcycle here.
H = Hornet
L = Lightning
F = Firebird
S = Spitfire
T = Thunderbolt
750cc A75 Triples
1969-70 A75R-101
1971 HD00101-A75R
1972 JG00101-A75R

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