Norton Motorcycle model identification, engine and frame numbers

Norton Motorcycle model identification, engine and frame numbers.

Over the years, I have had the pleasure of owning a few Norton motorcycles. Sadly, none of them were exotic models, but they were still a joy to own.

Inevitably, I needed to research model types, years of production and specific parts. The information is available, but it’s scattered on several sites and (in some cases) confusing. So, the information presented below on Norton numbers, is attempt to present the information in a clear manner.

Caveat: The information provided is just info gathered. While I believe it to be accurate, please do not solely rely on it. It’s there as a guide and you should double-check the information with a supplier, or trusted advisor. 

I cover the years 1923 to 1975 and offer information on Pre War and Post War Norton models. There are some gaps, but I’m working on that.

Norton motorcycle Model codes

Norton used a combination of Model codes, suffixes and year codes to help with identification. Over the years, they spiced things up a bit.

Initially, engine and frame numbers didn’t match, so if someone is offering you a “matching numbers” pre-war Norton, it’s either a massive coincidence, or you had better have a very close look at the number stamps. A little “correction” may have taken place at some point in the machine’s long history.

The Serial Numbers on the Frame and Engine from 1945 to 1974 should match.

The serial numbers from 1945 to 1960 should include a year letter code (See table below).

Finding Norton engine and frame numbers

Engine Numbers

The Engine Numbers are found on the front of the crankcase or on the left-hand crankcase just below the cylinder. The engine number might also include the engine dimensions, especially on the singles with the 79X100 mm bore and stroke. I have known the number on the barrel base match the engine number. I’ve seen this on a few 16H engines that I’ve had. I’m told it shows that it has retained the original barrel.

You might see other numbers and letters stamped on the casings. I stand corrected but I think they used to stamp batch numbers on the front left shoulder of the cases, particularly 1939 -45. Talking of war period engine numbers, I will create another page on this as it’s a specialist subject. The War Dept tended to stamp engines with their own identifiers. So, if you’re looking at a Norton engine with a WD Kite mark on it, the chances are that you won’t be able to date the engine in the usual way.

Frame Numbers

Feather Bed Frames: The serial numbers are located on the primary case side, rear frame gusset (below to the rear swing arm bolt). The Model code is written horizontal with the year letter (if one is present) and the unique number is written vertically.

Commando Frames: The serial numbers on the Commando Frames are numbered on a plate riveted to the headstock.

Small Twins: The frame numbers are stamped on the right-hand frame lug which carried the rear fork up to 1963. From then on, it was on the pillion footrest bracket.

Other Frames: The serial numbers are on the headstock.

Model Code Identification

Notes: Suffixes were sometimes added to denote a model variation.

• D = Deluxe Twin
• SS = Sports Special twins
• Q = Quieting Ramp Cams, used in some 1947 singles

Dating the year by a LETTER Stamp – 1946 – 1960

Pre-War – Norton engine or frame numbers – 1923 to 1939

These numbers are approximate. You will note that there is an overlap on each year change. It’s a guide.

Notes: 350cc machines from 1929 to 1939 had their own range of numbers.

• 350cc machines 1929 to 1936 – 1000 to 6200.
• 350cc machines 1937 to 1939 – 6201 to 10700.

Post-War – Norton engine or frame numbers – 1939 to 1973

Have a look though any Norton parts that I have for sale here