pw50 model and age?

[amhengineering]

hi i have bought my daughter a pw50 but i dont know how old it is or what model it is.
there isnt a frame number on the headstock may be early bikes didnt have stamped numbers i dont know.
i cant find any stickers with model numbers on and i cant find any date stamps on any parts.
the bike has a black frame silver wheels ,black tank and fenders and a red seat,the paint looks original do these colours relate to a certain model or yr.
the engine number is 4x4267532
can any one come up with the answers to these questions i would be very gratefull.

[flyinbrian84]

the engine number is the same as the frame number you probably have a year earlyer than a 75 it should be stamped everything was if it is not there than someone removed it, look on line for the number to yamaha give them the engin number as the frame number and they can tell you the year all the parts of the pw50 are the same with the exception on the early models some electral plugs are not the same but can be easly changed