I coded up this page to be a more all in one solution, Honda, Yamaha, VIN numbers and engine serials etc. I also made it automatically processes what you type as you type it, so most machines you only need about the first half of the VIN, or the first 10 for the 1980+ 17 digit VINs. The VIN is never sent to me/the website, so it's a more secure site than the ones that do send it (server logs and such could get leaked).
Supported machines so far:
Honda 3 wheelers (VIN or Engine Serial)
Kawasaki 3 wheelers (VIN only)
Yamaha 3 wheelers (VIN only)
http://atvmanual.com/honda/79-atc-atv-vin-decoder
Here's the pages if you'd like to manually decode your VIN (more models covered here currently).
Honda VIN Table
Kawasaki VIN Table
Suzuki VIN Table
Yamaha VIN Table
Hope you guys enjoy. I'm always open to ideas/suggestions. I have an idea floating in my head to make a per model/year spec page and add a link to the results for more info on the machine, like the spec page on 3ww with HP, MSRP etc. Let me know if you find any errors. In time I plan to add newer models and such in too like quads etc.
I have to come up with my own image to instruct where the VIN and engine serial number is located. I'm not a fan of ripping other people's work off or using service manual images (questionable if it's fair use or not).