Obtained a converted Zenoah engine and I don't know what I have.
On upper cylinder it says Zenoah 1650 this is followed by a circle with the numbers 1 thru 9 and the letters xyz around the outer edge.
In the middle of the circle there is the number 97.
Can anyone identify this engine?
Interested in knowing anything such as what it was originally used for as well as the size/power of the motor.

Thanks for the help.
CASSIDY