The bike you are looking at is called the "Moto-Bike," and was made by Yamaha. I have right here the article by Ray Hill (photos by A.J. Hand) from the August 1974 issue of Popular Science that shows a photo and describes it. The title of the article is "Moto-Bike: off-road bicycle built like a motorcycle."
According to the article, it sold in 1974 for $125.
You can see a much better photo here.
My book, Fat Tire Flyer: Repack and the Birth of Mountain Biking
is at your bookseller and on Amazon