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This article discusses some apparent confusion (I'm NOT surprised) over engine, frame, and other numbers and letters used by BMW.

NOTE!! BMW has used a quite different frame identification system for NON-U.S. motorcycles. There may be a serial number followed by one extra number, and then the TYPE of motorcycle. The first digits are the serial number, and you can enter them into any serial number search. This means that if you have 8 digits at the beginning, 7 are used for the serial number. I do NOT know what the 8th digit means.

In the OLD days, BMW simply used a serial number. Simple. Find the number on the engine, find the frame number. They may even have been the same number....usually were, actually.

Things got much more complicated later on. This posting is not going to straighten the mess out entirely; but, I hope, mostly.

The confusion really began to heighten with the introduction of the 17 character Vehicle Identification Number (VIN), which is a combination of letters and numbers. At first, BMW matched the serial numbers of frame and engine. 1980 was the transition year, and some anomalies for 1980-1981 production are around, so if you have a 1980-1981, do not be upset. At the end of 1983, with the introduction of the 1984 model year bikes, BMW decided not to match up these numbers. They said so officially, so if YOUR numbers DO match, don't blame me! Not only that, but BMW phased in something new....they were NO LONGER stamping the engine serial numbers next to the dipstick.  You can see that on 1984 and later.

Frame numbers were stamped at the steering head to 1982, then on the frame below the right cylinder. Early bikes will usually have a frame number on a tag in the steering head area.   Engine numbers up to 1983 were generally next to the dipstick. After 1983, and this was phased in, they MIGHT have moved to a milled engine pad, where any engine number MIGHT not be even the same system, IF THERE, as previously. Confused? Well, BMW put some weird stuff on that milled area.   On that engine pad, sometimes the pad was missing!...were lots more characters identifying more things, some not revealed to me nor anyone outside the factory. All that being said, some bikes don't conform to the published standards, limited as they are, for that engine pad....so, read on...

BMW has also not held itself strictly to its bulletins (Service Information, or SI) on these matters, so one may well see some combinations or variances.

On models with a VIN, that number is probably; but may not be all there, or is on the steering head, or partially there, on some 1980-1982 calendar models..., where they are fully, you will find all 17 digits (ALWAYS 17), on your lower right side frame tubing, roughly in line with the right side carburetor. Again, the transition period was 1982, and you may find yours on the steering head area plate/tag.   You may also find it on a metallized tag on top of the driveshaft housing...which may not agree in ONE letter ID (year); and, you may have funny other things going on..

Take everything on this page with a grain of salt, because motorcycles shipped to other countries than the U.S.A., may be STRANGE in identifications.

You might also see that mentioned large mettalized label with a VIN on the top of the driveshaft tube. In general, the VIN there will agree with the VIN on the steering head or lower right frame. In a FEW cases, there may be a single LETTER difference. That letter is the YEAR identification letter. An example might be a late 1983-built RT. The UNofficial information ... is that BMW did not submit this end of production 1983, early enough for California smog testing. So BMW cleverly put a letter (E) in the VIN number on that driveshaft label showing it as a 1984, so it passes the smog requirements, yet the FRAME number, the number that is "official" for registration, has the letter (D) showing a 1983 model. The actual facts on this discrepancy are not known for sure by me. But, it does lend itself to folks possibly registering/titling a bike for either year.

On many models you may find a set of characters stamped on that mentioned flat boss area of the crankcase, left front side above the frame tubing. These are a combination of letters and numbers that signify the model year, the week of (engine??) production, a sequencing number, and some Environmental Protection Agency [EPA] identification coding on the bottom line. If you have this set of characters and they match an engine serial number (which may or may not be at the old place, next to the oil dipstick...THAT was dropped too), hey, you have a strange one.

Re: the flat boss area:
The top line will have something like:
83 23 2175
That is supposed to mean that the engine is an 83 model, produced in the 23rd week, and has a sequence code of 2175. BMW issued a SI, implying, but not specifically stating, that these things will identify the bike, for police or other reasons. Do not count on that 23rd week as being when your bike was actually produced. Chances are pretty good your bike was assembled later. Also do not try to apply mathematics to the serial number range of total production you may find posted here and there for your year and model, you will probably get more confused, it probably will not correlate.

The Elves at BMW know, and they don't talk much. To me.

Under the above may be a line, perhaps something like:
DBM098042A3
That is some sort of certification coding. If you find out how to decode it reliably, let me know. Supposedly it identifies the engine FAMILY, for certification purposes.

BMW has a SI Bulletin out on these things...well some of these things...and that SI seems NOT to be entirely accurate. For example, the SI says that the week is listed first, and I am hard pressed to remember any year with 83 weeks. Since the Germans take a huge amount of time off for vacations and so on, and the factory shuts down for that every year, that might account for some of it (I am kidding here). The SI also says that the certification coding is the same for all engines...it is supposed to be...meaning all R100 engines are one family code....... Suuuurrre it is!

***NOTE: Special records as to transmission number, key codes, and factory identifications of things that they do not like to let us have, are recorded at the factory, and they computer code them by VIN numbers. Supposedly some of this stuff is available to law enforcement agencies, for theft identification. RIIIIGHT! You might find stamped serial numbers or sequence numbers on the transmission housing, inside area, or even to the left just barely below the aircleaner housing.

OK, let us get to the final part of this posting, interpreting those 17 digit VIN numbers. THIS you can trust (except for that one year anomaly I mentioned above)!!

I have BMW's own bulletin on this, so let's use it. It happens to correspond to what I know about vehicles, having been a paid part-time registrator of vehicles for a few years.

Here is a sample, for a R65. I shall also list underneath, my own 1983 R100RT...so I can discuss a few things.

The R65: WB10 364 0 4 B 6 385 003
{the actual VIN would not have spaces}

The R100RT: WB10 449 0 9 D 6 243 160
{the actual VIN would not have spaces}

Now, let us take that VIN code in order:

W means that the manufacturer was In Europe.
Combined with the B, it means BMW-AG, Munich, West Germany.

1 means motorcycle.
0 means a two wheel motorcycle (yeah, yeah, I know...).

((so you think your Harley was shipped by the factory as a trike or sidecar unit....better LOOK))

NOTE: BMW may, in parts list and other places, show a MODEL CODE as 364 (that is R65) and 449 (that is R100RT). They MIGHT have a zero in front of that number.

Going onwards with the decoding, after the 0 meaning a two wheel motorcycle:
3 (R65)...or the 4 (R100RT) identifies the LINE type.
In the case of the R65, the line type is 248/1.

You are a Member of a Club that states in its purposes, the 247 type...are you confused?

(confused??)

6 (R65) identifies the engine type, that is, number of cylinders, whether gasoline or diesel, and the size of the engine, and if 2 or 4 stroke. It is a BMW in-house coding.

The next digit, for the R65, a 4, is the NET horsepower. In this instance, the 4 stands for 45 BHP. Astute observers may notice that in the R100RT the claimed horsepower by this coding is 90 or more. yeah, riiiight!

The following 0 had no meaning, that is, it was there and had no special meaning on my version of the BMW SI.

Next comes a check digit, the 4 in the case of the R65, the 9 in the case of the R100RT. Check digits have many uses, primarily it is a digit to tell a computer if things are possibly wrong in the rest of the sequence of characters.

Then, the letter identifying the year:

Notice the B in 10th position for the R65, and D in 10th position for the R100RT. That letter is a YEAR code. This system is for U.S. production, that began in 1980.
1980 bikes used A
1981 bikes used B
1982 bikes used C
1983 bikes used D
1984 bikes used E
1985 bikes used F
1986 bikes used G
1987 bikes used H
1988 bikes used J
1989 bikes used K
1990 bikes used L
1991 bikes used M
1992 bikes used N
1993 bikes used P
1994 bikes used R
1995 (last of airheads)...S

there was no letter I, nor O, and for your information, Q, U and Z are also never used.

NOTE!!...This page is concerned with AIRHEADS....not other BMW models. I know of instances where K bikes were made in June of 1992, and were 1993 official model year bikes.

NOTE: Beginning in 2001, the character that was a letter identifying the year, became a digit. for 2001 it is a 1, for 2002, it is a 2...easy, Eh?

Lastly, how to explain the official sequence number, which you might as well call the serial number, because that is what it REALLY WAS, a long time ago. You might even find that sequence (serial) number next to your dipstick, and agreeing with the frame number.   BUT, when the dipstick serial number was dropped, in 1984, the only serial, well, sequence serial, and I am NOT totally sure it really is a serial....appears to be more of a series sequencing, with jumps for production changes.
So, only BMW seems to know how to correlate engines-to-frames, AFTER the dipstick serial was eliminated...and there MAY be some other foolery too.

Officially, according to the adopted International Standards for official VIN 17 character numbers, the 11th position, in the examples, this is a "6", it is to identify the assembly plant.

For a quick way of determining, on many models and especially later years, the manufacturing model year:
http://www.bmw-z1.com/VIN/VINdecode-e.cgi

Here is another website URL, which you may prefer, which uses a different chart format for serial/VIN's:
    http://bmbikes.co.uk/enginechassis.htm

Revisions:
02/13/2006: minor updates, and also changed the BMBIKES.co.uk URL.
11/27/2007: change to 67A from 67