Hello I'm new to the club and was wondering if there is a way to tell the year of an engine I have off a DT 125 so I can buy parts for it? 

Yip,,,,put up the number on case,, is it air-cooled ,?  

E17e is that the number? 

Unusual"   ,most start with a number [ 455- 000-000]      ,what country you in ,is it old or a modern DT175 [ Far east]  

https://www.motorcyclespareparts.eu/en/yamaha-parts/yamaha-model-prefix-motorcycles-1970-1994