Classic Motorcycle Identification

of 01

Classic Motorcycle Identification

No tank badges, no decals on the side panels, incorrect fenders and lights, so what is this bike?. John H Glimmerveen Licensed to

Occasionally a motorcycle will be offered for sale with history unknown. This happens both with private sales and auctions (although this is rare).

Identifying a classic or vintage motorcycle is generally easy: stickers and badges are all over motorcycles, most have VIN (Vehicle Identification Numbers), and some have the name of the manufacturer cast into their engine cases. But every now and then, a motorcycle comes up for sale with none of these telltale pieces intact, which calls for some research via a process of elimination.

Although obvious, determining the maker or manufacturer of a motorcycle is the starting point. But this is not always as easy as it sounds. For example, the motorcycle in the photograph has no obvious markings. It is a large machine with a side valve engine and girder front forks from around the middle 20s to the 40s. One feature that will help to determine the manufacturer is the engine crank casings which have a cable entering them on the top left side.

Looking for clues on a machine in this way will eventually lead to the make, model and year of any machine being discovered.

On the rare occasions when the manufacturer's name is not obvious (gas tank, side panels or VIN plate), some disassembly may be necessary. The easiest location to look for the identity of the manufacturer is on the wiring harness. Many manufacturers had model specific harnesses made with telltale part numbers and/or the manufacturer’s name printed on an attached label. During the assembly process of a motorcycle, a lot of wiring is positioned inside the headlight and it is here that labels can often be found.

Removing engine casings is the next phase in attempting to identify the manufacturer. Cast aluminum engine covers often have the manufacturer’s names cast into them. Alternatively, the castings may have an emblem or trademark representing the manufacturer cast into them.

Other locations to find identification names or marks include:

  • Under the front fork triple clamps
  • Stamped into a muffler
  • Inside valve covers (4-strokes)
  • Wheel rims or hubs
  • Brake shoes
  • Brake back plates
  • Side panels or covers
  • Inside switch assemblies
  • Light lenses
  • Footrest or handlebar rubbers
  • Stamped into steel seat pans
  • Stamped into the frame

If, after checking all these components for the manufacturer's name, no name or emblem is found anywhere on the motorcycle, the only option left is to proceed via a process of elimination. For example, what size and configuration is the engine, how many speeds does the gearbox have, what size wheels/tires does the bike have, what shape is the gas tank (most manufacturers had a unique shape for their tanks), what type of front forks are fitted (this will help to identify the year).

Owners Clubs

Once the make has been established, the model and year can be researched. For the majority of makes, there is an owner’s club. The ​clubs and their members offer a wealth of knowledge on specific manufacturers.

A search online will often produce much information about a specific make or model, but the researcher must exercise caution as some websites are very misleading. Often, if the manufacturer is still in business, researchers will find an official website complete with a history of the company and the machines it has manufactured.


Classic motorcycle museums are an excellent source of information too; many have books or magazine articles from the various periods available. In addition, the staff at museums often has extensive knowledge of the machines on display (a polite inquiry letter with a photograph may find the answer).

Other written information sources include workshop manuals. Haynes has published more than 130 titles since they started in 1965 with manuals available for machines manufactured as early as 1947. Clymer Publications in the US have manuals available for motorcycles back to the Panhead Harley Davidson’s of 1948.

One way to find an original manual online is an advanced search through Google Books. This site contains millions of out-of-print books.

Finally, old books have always been a major source of information on classic and vintage motorcycles. All of the major book publishers and distributors offer titles specific to individual manufacturers, often offering a timeline of the different models produced.

Note: The motorcycle in the photograph is believed to be a British War Department BSA M20 500-cc side valve produced between 1941-5. It has the wrong mud guards and wrong backlight; there is also some doubt about the headlight. Note: The M20 was a 500-cc machine and the M21 a 600-cc variant.