FRAME AND MODEL AND VIN NUMBERS, OH MY!!! Okay, gather 'round friends and prepare yourself, 'cause we're about to go down the rabbit hole...... It goes without saying that the proper and correct identification of your bike is important for a number of purposes----first and foremost, so that you can order the correct parts for it! But equally important is making sure that your title is correctly identifying your bike for registration, title, and licensing purposes, as well as for insurance registration purposes, etc. Our STRONGEST advice is to not rely on the information on your title, bill of sale, insurance documents, state registration certificates, what the former owner claimed, or any other PIECE OF PAPER-----always go "right to the horse's mouth"----or in this case, your bike's frame and engine case, and absolutely verify 100% what bike you actually have! You'd would be quite surprised how many people we come across who are ordering parts, for example, for a 1981 model XJ-whatever because that's what it was sold to them as (or titled as), when in reality they have a 1982 model! YOUR FRAME AND ENGINE CASE ID NUMBERS ALWAYS SPEAKS THE REAL TRUTH! Some typed-up piece of paper from a government or insurance company clerk does not always fall into that same category of certainty! ALSO: verify that the engine in your bike is the original engine! Since many of the XJ-series engines are physically interchangable with each other, you never know what's been done over the years as far as engine-swapping is concerned! Rings and pistons from a 650 model engine are NOT going to fit a 750 engine, even if the 750 engine is installed in an XJ650 frame!!! So please---spend the 90 seconds or so necessary to determine whether the engine is original to the bike, and if not, what year/make/model bike that the engine came from. The procedure for doing this is described completely further below. And finally, if you take a little bit of study time all of the information below, then soon you, too, can start "code talking" about having a "1982 5N8 model" or a "750MK" and really impress the other guys at the shop with your intimate and devil-is-in-the-details knowledge about all things Yamaha...... Okay, as is proper with any good training video, we're going to start with the big picture and then work down to the nitty-gritty details. So, buckle up, or hunker down, or whatever your favorite metaphor is------because there's going to be a pretty smooth take-off, but then expect some bumps in the road ahead. Or, if you’re pressed for time like the rest of us, first go here: http://www.xj4ever.com/catalog/frame-engine-id.pdf and then here: http://www.dissingermoto.com NUMBERS, NUMBERS-----EVERYWHERE: In order to provide a simple basis of communication both internally (between the engineering, sales, production, marketing, and other departments within a company) and also externally (retail dealers, customers, governmental and other outside parties), vehicle manufacturers of all kinds choose to (and are now required to) provide unique "shorthand" codes for each particular unit that they offer for sale. The most commonly used code is what is commonly known as a VIN or Vehicle Identification Number----a sort of "DNA fingerprint" for an individual product. Besides containing a unique serial number for an individual bike, the VIN number also identifies unique characteristics of a bike, such as the manufacturer, the model or "platform" identification, certain optional characteristics, the year of manufacture, etc. Before we get down to deciphering a VIN number, let's take a brief step back in time, and recognize that prior to 1981, there was no real set standard for how VIN numbers had to be assigned.....in other words, the VIN Numbers used (by any vehicle manufacturer) prior to 1981 was more-or-less an internal-use number, and could be conjured up in whatever way struck a manufacturer's fancy and served their internal needs. Starting in the late 1970's, with the proliferation of manufacturers, vehicle production volumes, and international sales, a solution to the "VIN dilemma" was suggested by the International Standards Organization (outlined in ISO Standard #3779, for the ultra-curious), and this standard was adopted and required to be used by all manufacturers that sold vehicles into the USA by the National Highway Traffic Saftey Administration (NHTSA) as of 1981. This is when the familiar, still-used-today 17-position VIN number came into use, and similar structured VIN formats were also adopted by Canada, the European countries, and many other countries around the world. Prior to 1981, manufacturers could use a VIN number length of their choice, and Yamaha was no exception in this regard. In fact, because of the difficulty encountered with implementing this required 1981 changeover, Yamaha (and some other manufacturers) were granted a 9-month "stay of execution" for their 1981 model-year offerings, where they could still use their older (shorter) version VIN numbers to identify their products. Thus 1980, 1981, and perhaps even some very early production 1982 model-year bikes use a shorter VIN number that appears on the frame of the bike (more about this later), and may also include a printed paper decal that lists a different (longer) VIN number that is the "extended", 17-posiiton version of the original, shorter VIN number. Although for the purposes of absolutely, positively identifying your bike for exactly what it "is", the differences between the shorty VIN and the longer VIN are minor---although since the full 17-position VIN number contains more information, it makes the deciphering process a bit less time-consuming, but rest assured that----armed with the proper information---even a "shorty VIN" can be just as accurately and fully de-coded.