That's not a date on the barrel, never known any manufacturer to cast in dates. Exception being with the clock style date casting, usually on plastics
Cyclegod was right, look closer its says 198L meaning 0.198 litre.
Looks like an 84 model by the sidecovers
Not sure, did they make a 175 in 80, I thought 81 was the first KDX?
Will make a good Vinduro ride when you have it sorted.