Yamaha models can be identified by locating and decoding the crankcase engine number. Yamaha uses a standardized numbering system, which is broken into four sections: model code, basic part number, design code and the finish code. Because the crankcase engine number is actually the part number, improper identification might occur if the engine has been replaced, or if an interchangeable case has been swapped with the original. According to Tangedal.no, the first section of the part number identifies the Yamaha model.
Locate the engine number. Yamaha engine numbers normally are located on the top of the crankcase, next to the clutch cover on the right side of the engine while sitting on the vehicle.
Write this number down for referencing. According to Tangedal.no's Yamaha part structure PDF, the first three positions of the 12-position code designate the model and is either alpha-numeric or all digits -- 2A0, for example.
Look the model number up on a Yamaha model listing. A listing similar to the ones found on Off-Road and Net Bikes.com should be consulted to properly identify the model. The model year is included within the code, as each year is assigned a different code unique to the year of manufacture. Off-Road.com is primarily a dirt bike/off road reference, Net Bikes references street models.
Because VINs and engine numbers are different, the VIN should be used for proper identification, as the engine might have been replaced. The VIN is located on the steering head pipe, which is the the short tube at the forward part of the frame, near the handle bar mount. VIN identification can be made at Motoverse.com.