Identifying Engine and Frame Numbers

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Most Vincent owners regard the engine as the most important part of the motorcycle. However, in the United Kingdom the DVLA regard the Upper Frame Member headstock number as the frame part used to identify a Vincent or H.R.D. Motorcycle.

Pre-War
Before World War II, the Vincent H.R.D. factory started to adopt a code and numbering system that some Vincent enthusiasts recognise as bearing some similarity to the post-war machines.

JAP, Rudge and Villiers engined Vincents didn't seem to follow any pattern, so if you're thinking of buying such a machine, you'd be well advised to do your homework so you know exactly what you're buying.

A Pre-War Engine Number is usually in the form of M615
The engine prefix USUALLY denotes the model type.
V=Rapide
M=Meteor
C=Comet
TTC=Comet Special
TTR=TT Replica
TT=TT Machine

A Pre-War Upper Frame Number is usually in the form of D1285
The Upper Frame Member (UFM) number is stamped on the steering head - the number in this position is the number used by the DVLA (UK) for all official records (MOT and Registration documents).

A Rear Frame Member Number is usually in the form of D1285
The Rear Frame Member (RFM) number is stamped on the left hand side near the wheel spindle. This may (or may not) match the number stamped on the Upper Frame Member. If the Rear Frame number doesn't match the Upper Frame number, please don't assume your bike is 'non matching'. The only way of checking what numbers a machine left the factory with is by checking the Vincent Factory Records.

Frame numbers that start with a 'D' are usually single cylinder machines, and those 'DV' are usually twin cylinder machines, but as with all things Vincent-related, there are some exceptions. As always, the only way of checking what numbers a machine left the factory with is by checking the Vincent Factory Records.
D
=Single Cylinder Machine Frame Part (note some Model J & Model P frames also used this prefix).
DV=Twin Cylinder Machine Frame Part (Rapide — most but not all).

The above covers most options — but not all — there were some exceptions

Post-War
After World War II, the Vincent H.R.D. factory adopted a code and numbering system which carried a great deal of information in the engine number. The number appears on the left-hand side of the crankcase, just below the front cylinder barrel.

eng_no_small.jpg
A Post-War Engine Number is usually in the form of
F10AB/1/1234

Engine Type: F=Four stroke. T=Two stroke.
Cubic Capacity: 10=1000cc. 5=500cc. 07=70cc. 05=50cc (eg. Firefly Cyclemotor).
Engine Material: A=Aluminium. M=Magnesium Alloy.
Engine Purpose: B=Bicycle. M=Marine. U=Utility.
Twin Models (between the obliques): /1/=Series 'B' or 'C' Rapide. /1A/=non-standard model (including White Shadow). /1B/=Series 'B' or 'C' Black Shadow. /1C/=Series 'B' or 'C' Black Lightning. /2/=Series 'D' Rapide or Black Knight. /2B/=Series 'D' Black Shadow or Black Prince.
Single Models (between the obliques): /2/=Series 'B' Meteor. /2A/=Series 'C' Comet. /2B/=Series 'B' or 'C' Grey Flash. /3A/=Series 'D' Comet or Victor. /4/ and /5/ usually indicates that the crankcases are reproduction.

ufm_no_small.jpg
An Upper Frame Member Number is usually in the form of
RC/1/1234/B/D

The Upper Frame Member (UFM) number is stamped on the steering head - the number in this position is the number used by the DVLA (UK) for all official records (MOT and Registration documents).

The Upper Frame Member (UFM) number can be broken down into its prefix, serial number and sometimes a suffix.


Frame Number Prefix
R
=Series 'B' Twin
R/1/=Series 'B' Meteor
RC=Series 'C' Twin
RC/1/=Series 'C' Comet
RC/1A/=Series 'C' Grey Flash
RD=Series 'D' Twin
RD/1/=Series 'D' Single

Frame Number Suffix
B
=Black Shadow
/A=Metric taper wheel bearings (front wheel only)
/B=Metric taper wheel bearings (rear wheel only)
/C=Metric taper wheel bearings (both wheels)
/D=Ball wheel bearings with circlip
/E=Ball wheel bearings with lock rings
/F=Series 'D' Black Knight
B/F=Series 'D' Black Prince

So, do not confuse /B as a Black Shadow as it refers to wheel bearings, but you can get B/B which is Black Shadow with metric bearings in the rear wheel only.

If the Upper Frame Member number doesn't follow the usually quoted difference rule between engine and frame numbers, please don't assume your bike is 'non matching'. The only way of checking what numbers a machine left the factory with is by checking the Vincent Factory Records.



rfm_no_small.jpg
A Rear Frame Member Number is usually in the form of RC/1/1234

The Rear Frame Member (RFM) number is stamped on the left hand side near the wheel spindle. This may (or may not) match the number stamped on the Upper Frame Member. For breakdown of RFM code see UFM above. If the Rear Frame number doesn't match the Upper Frame number, please don't assume your bike is 'non matching'. The only way of checking what numbers a machine left the factory with is by checking the Vincent Factory Records.



twin_single_c_case_no_small.jpg
Crankcase Mating Numbers are usually in the form of any combination of numbers and figures (eg. 3C and 3C)

The crankcase mating numbers on a Twin cylinder machine are stamped BETWEEN the cylinders, on both halves of the crankcases.

The crankcase mating numbers on a Single cylinder machine are usually stamped BEHIND the cylinder, on both halves of the crankcases, (but not always).

Restamping Engine and Frame Parts
Sadly, there is a misconception amongst some uneducated Vincent owners that all Vincents made since 1946 follow a usually quoted ‘rule’ difference between the engine and frame numbers. Please don't consider this 'rule' to be true. The Vincent H.R.D. Owners Club have documented examples of people re-stamping engine and frame parts to fit the 'rule', only to find out later, their machine didn't follow the ‘rule’ when it left the factory - so they probably removed the original numbers and effectively de-valued their motorcycle. The only way of checking what numbers a machine left the factory with is by checking the Vincent Factory Records.

Furthermore, a prospective buyer is well-advised to look at the numbers carefully because it is all too easy to 'upgrade' a model by stamping in an extra character, and there are also a number of stolen Vincents in circulation. However, do not automatically assume that an irregular stamping is a fake. The first part of the number was stamped on routinely before machined castings were put into the factory stores, whereas the final designation and serial number were only stamped when the engine was built - and frequently with different stamping styles.

Please make sure you tell us the complete bikes you own, as well as engine and frame parts. On a number of occasions we have been able to reunite owners with stolen machines. Rest assured our confidential Machine Register is accessible to just two Club Officials and is not available anywhere on the internet.

To tell us what bikes you own click HERE.

If you have a question of a more general nature relating to engine and frame numbers that members of our forum website community might be able to answer, click HERE.

Never rely on Certificates of Authenticity or Dating Certificates issued years ago, nor information provided by sellers. You should always satisfy yourself that you know what you’re buying before you bid/buy. Always contact the Machine Registrar or Researcher before buying a Vincent. Always do your own due diligence.

To contact the Vincent H.R.D. Owners Club Machine Registrar and Machine Researcher click HERE.
 
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