Since we've agreed that we're putting together a 1981 model, then of course the tenth position is---from the chart above---the letter "B":
NOTE: we're going to confuse you now----and it won't be the last time. The year-designation letter codes listed above ONLY PERTAIN TO THE MODEL YEAR CODE USED IN THE VIN.
There is an alternative way of identifying the year of your bike by the Yamaha marketing "model name" of your bike, and it also uses a letter code for such year-model identification purposes, BUT SUCH MODEL DESIGNATION "NAMES" USE A DIFFERENT LETTER CODE THAN WHAT IS THE VIN "YEAR" IDENTIFIER CODE!
Okay, deep breath now, keep going, and forget about that last paragraph for now----but, do keep it in mind for later.........
JYA4H7006B -a- -bcdefg
The 11th position of a VIN number (-a-) is the location of the ASSEMBLY PLANT where the bike was made. All bikes in this era were produced in Japan, probably at their Iwata City production facility, which was the "A" location. Thus the 11th position of all XJ model bikes will be the letter "A":
JYA4H7006BA -bcdefg
And now we're down to the last 6 positions of the full VIN, and this is the unique, sequential "serial number" of each individual bike. Your own bike has a serial number that is different than every other one ever produced for your model and year bike.
For various reasons, Yamaha assigned a range of serial numbers for each bike year and model, and these numbers did not normally start with the number "000001". The starting point for each serial number differs by year and model. For the 1981 XJ650 Maxim used in this example, the serial number range starts with serial number "100101". Each subsequent 1981 XJ650 Maxim model 4H7 destined for the US marketplace got the next higher serial number, thus the second bike off the assembly line was #100102, etc.
Let's pretend that this was the 1,356th 1981 XJ650 Maxim destined for the US marketplace. So starting with the 100101 number, we add 1,356 to it, and get: 101457 ( = 1,356 + 100,101).
So our final VIN for this particular bike is:
JYA4H7006BA101457
which, breaking it down into its component, meaningful parts again, is this:
JYA -4H700- -6- -B- -A- -101457
Now, with all of the above in mind, we can see from the above 17-position VIN that most of the information that is USEFUL is really just the MODEL ID part (4H700), the year (B), and the unique serial number portion (101457).
In fact, in the model ID part, since positions 4 and 5 were not used by Yamaha to designate anything at all, and thus are always "00", then really only the model ID part (4H7) contain any useful infromation:
4H7---the model identification portion, in this case meaning a 1980 or 1981 XJ650 Maxim.
B---the model year, in this case 1981.
101457---the unique production number ("serial number") of this particular bike.
And Here's Where We Go Backwards:
From the example above, we see that although a full 17-position VIN number was required of Yamaha (and everyone else) beginning in 1981, all of the useful information contained in the 17-position VIN can just as easily be captured by a "shorty" version of the VIN, just as Yamaha used prior to 1981:
4H7-101457
That smaller string of numbers, above, is what was considered a "VIN" number for 1981 and prior years.
BUT WAIT!, I hear you cry.........where is that useful piece of information called the "YEAR"? (in the full "long VIN", recall that the 10th position uses a letter code to designate the model YEAR, and in our example it's the letter "B", since B = 1981).
Good question. And here's the good answer:
Recall this statement from above:
"For various reasons, Yamaha assigned a range of serial numbers for each bike year and model, and these numbers did not start with the number 000001."
Well, one of those reasons is that by assigning a defined RANGE of unique serial numbers to each year and model of bike, that unique serial number not only identifies the individual unit of production (thus completely serving the "serial number, DNA-fingerprint" purpose of that number), but also serves as a way of identifying the year of production, too!
Here, as an example, for the 1980 and 1981 XJ650 Maxim (4H7) models, we have:
1980: starting serial number of 000101
1981: starting serial number of 100101
Thus, if you come across this shorty VIN:
4H7-021338
then you know that since the "serial number" is less than the number 100,101 (which is the starting serial number for 1981 models), then it's a 1980 XJ650 Maxim.
But when you see this shorty VIN, as from our "Build-A-Bike" example above:
4H7-101457
then since that serial number is greater than the "100101" starting point for 1981 model year bikes, then you automatically know that it's a 1981 (and not a 1980) "4H7" bike (an XJ650 Maxim).
And In Confusion, Whoops, I Meant "Conclusion":
Because the rules changed in 1981, and forced vehicle builders to use a structured, standardized 17-position format for the VIN, the 1980 and 1981 model bikes can have both the long or the short (or both) VIN numbers on the bike. With a little bit of additional information (the serial number range), you can fully "translate" the shorty VIN into the longer 17-position VIN. The longer VIN is standardized, and I suppose that's good; and it also explicitly codes the model year (in the 10th position), which is really the ONLY feature that the shorty VIN does not clearly encode.
Now, onto the burning questions:
Where on my bike is this long, or short, or any other VIN's?:
I don't have the slightest idea.........
Just kidding. The number(s) are in at least two places, and on most bikes, three locations:
1) On the right side of the steering "neck" or tube (or "head pipe" as it is sometimes called), you'll find stamped the shorty VIN (1980 and early-1982 models) or the full 17-positions VIN (late-1981 and later years) is stamped, vertically, into the frame tube.
2) On the left side of the steering "neck" or tube, there will be a white printed decal that will have the full 17-position VIN, along with typical boilerplate "conforms with regulations blah-blah-blah" wording. NOTE: it is on this decal, and only on this decal, that the date of your bike's manufacture is also printed, in a MM/YY format (i.e. 10/81 = October 1981 = a 1982 model year bike).
Note that for late-1981 year bikes and on, that the full 17-position VIN number appears on both the left-side decal and right-side stamping of the frame's steering neck tube.
On some later model bikes----primarily late-model XJ900 models----this ID "decal" became a metal plate that was rivited to the right side frame down-tube.
3) On the engine case, just behind or beside the clutch cover on the right side of the engine, on a small, flat machined pad that faces up (towards the sky). On XJ550 models, this pad is oriented left-to-right on the engine case, while on all other models it is oriented front-to-back.
What will you find on this pad?
The "shorty" VIN, as described previously. In our 1981 XJ650 Maxim, example, this flat pad would have this number stamped into it (as long as the engine is the original engine that came with the bike):
4H7-101457
Note that it does not matter what year your bike is; even after 1981, the number stamped onto this engine case pad is ALWAYS the "shorty VIN" number, and never the 17-position VIN.
From our discussion above, it is clear that if the engine in the bike is the original engine, then this number on the engine case will match, exactly, the shorty VIN on the right side of frame neck tube (1980 to early-1981 models), or, working backwards, to the model ID (4H7) and unique serial number (101457) of the longer VIN on 1982-later models.
Also, in situations where the engine has been replaced, you can actually figure out not only what engine it is (from the shorty VIN stamped onto the engine case), but you can actually work out the actual VIN number of the bike that such engine came from! All you need to know is the model ID codes (listed below), the serial number ranges (also listed below), and from that you can figure out the YEAR of the engine (and thus the bike).......giving you that "missing" bit of information that the full 17-position VIN does explicitly code for.....and then, using the "check digit" computation routine, you can actually calculate the full, complete VIN for the bike that an engine came from!
Now that's some kinda special party trick, you gotta admit!