Hi, Can anyone help ID this bike? Unfortunately I only have half of the bike in the photo.
It was a bike rental in Greece in 1993, but I guess it is earlier. From what I remember, it was a small bike - I would say 125cc maximum, but may have been smaller.
I would be looking for model and year if possible
 

Hello IDG . . . Welcome to the forum.

I'm not an expert on foreign Yamaha models, but the features and styling lead me to believe it's ether a DT125 or DT175 model from somewhere around 1978.
   
I must say, I've never seen a model quite like this one . . . It has a rather odd mix of parts that I wouldn't expect  to see together.

The fuel tank looks similar to some Honda or Suzuki models, and Yamaha normally attached their headlights with fork brackets.
Perhaps it's a modified bike that the rental company created for themselves.

I know even less than Enduronut... one thing that struck me is what appears to be part of a monoshock swingarm is silver and appears to have a square or rectangular cross-section?

That might date it later as all the earlier monoshock models I've seen from around the world were made of round tubing painted black... one of our UK friends might know when the silver rectangular swingarms first showed up on the DT125/175? I think it was 1979 or 80? Not sure as we only had the black round tubing rear arms and the US DT125/175 model last year here was 1981.

I was wondering if it might be an XT of some description.

Perhaps IDG could tell us if it was 2 or 4 stroke?

Looks like a two stroke from what I can see of the pipe?

Anyway, rack reminded me of my later 1988-1990 US DT50's...  It's definitely not one of those... 

BUT I did find a few pictures of DT50MX models that had the same round headlight with mount that does not appear to clamp to fork tubes and similar gas tank shape?  So maybe a DT50MX or DT80MX?