300/440/550 How to tell the year of a kawasaki motor

[chese]

Hey I am interested in a jet ski on craigslist, it's a 550 with a 1981 hull but he says he doesn't know the year of the engine, does anyone know a way to tell?

 

[SUPERJET-113]

There really is no way to tell the year of the engine. As you probably know the last 2 digits are the year of the hull, but the motor serial numbers dont work that way. Im sure there is some code to the engine serial number, but I dont know anybody taht knows it or have never heard of the code.
All those old piston port 550 engines are all the same. just make sure it has good compression and runs right under a load(on the water).
Good luck!