[Partsguy]

Hmmm, I guessed, I searched, I was wrong several times.Are we in the '70 or '60s? Smaller than 250cc ?

 

[Partsguy]

Can't nail down the year, but some educating guessing and I think I got it. Fairly rare little,well mid size for the day Yamaha.

 

[Partsguy]

The third pic was the biggest clue for me.
1975 ?