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BMW Airhead (& some twins prior to Airheads) Motorcycles
Model differences over the years. Technical details of importance.
Including a chart on weights and capacities.
Plus information to identify the model/year, if you do not have a serial number, etc.
© Copyright 2018, R. Fleischer
Identifying the year of production by serial and/or VIN number:
Beginning in 1980, and the process not completed until sometime in 1981, U.S.A.-shipped bikes from BMW changed from a pure serial number to a Vehicle Identification Number (VIN). This new type of 'number' is a combination of numerals and alphabet letters, and the total length is always 17 characters. The tenth position character (beginning from the left) is the official production year. As an example, for 1980, that was an "A". Each year following was one letter further in the alphabet. I, O, Q, U, Z, were all skipped. Beginning in 2001, a digit was used, with 2001 being 1, 2002 being 2, etc. Non-U.S. models might not use the 17 character VIN number system. In every instance, BMW records can use the last seven characters, which are almost always just numbers to identify the year and model; and, indirectly, the color and how equipped when it left the factory. All brands of motor vehicles sold in the USA since the 1980-1981 transition era use the same 17 character VIN system.
For BMW vehicles, there can be confusion between the year of manufacture and the model year. This has sometimes caused problems with titles and registrations with various States. The actual "model year" motorcycle could have been produced near the end of the prior calendar year, due to the BMW company-wide vacation month in August and restart of production immediately after that vacation, in September. There are exceptions & anomalies ...most of these are such as when a BMW bike was manufactured even earlier and mysteriously is identified by BMW as the following year's model. This has happened with some Airheads and some Classic K bikes now and then. There is sometimes additional confusion, because, for 1984, BMW stopped stamping the last 7 characters of the 17 character VIN, always a 7 digit number, next to the oil dipstick of all engines.
For very considerably more information about VIN and Serial numbers, how to read all 17 characters of VIN's, the sequencing, the anomalies, etc. see the following article: http://bmwmotorcycletech.info/IDnumbrs.htm
"Airheads", for the purpose of this website, and this article, mean BMW motorcycles with the 2 cylinder boxer-layout engine style with two valves in each head, as produced beginning 12/1969 as 1970 /5 models. Airheads are generally considered as being in production into 1995 and possibly a few into 1996. Airheads are not the other boxer type motors that BMW produced, slangly called the Oilhead, Hexhead, etc. Those are considered air and oil cooled, and have a very different type of engine design, which are also all fuel injected. Slash 2 is used generically, to mean the models more or less immediately before the Airheads; that is, before 1970. I don't get deeply into them. They were generally produced in the fifties and sixties.
The details in this article are not to be considered to list every year's change. I will add details to this article now and then.
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