yamaha model codes

[4cylinders]

hey, where's the best place to find out yamahas model codes? found a 4 cylinder 750 engine stamped 4u8, what is it, year model. may trade for a shaft engine I have, would like to build a yamaha 4cylinder what ever.

[4cylinders]

hey, found the info I needed, It's an 81 xj550, oh well, any one interested? nice little engine. chain drive, pretty small for a 4 cylinder.