Wolfchen
Ace of dogma
I was curious about the first XS1B 650s and used search but didn't find anything specific on the bike's primary development.
Here's a more detailed account of the successful factory effort using SOHC valve technology from Toyota. Ford used a Yamaha designed 3.0 liter engine in their now famous SHO V-6 and 3.4L V-8 engines.
http://www.classicyams.com/street-bikes/4-stroke/yamaha-xs1-development-story.html
There was another article about Yamaha engineers initial disappointment with the engine's low power output and how it was dealt with but I'd lost the text.
Here's a more detailed account of the successful factory effort using SOHC valve technology from Toyota. Ford used a Yamaha designed 3.0 liter engine in their now famous SHO V-6 and 3.4L V-8 engines.
http://www.classicyams.com/street-bikes/4-stroke/yamaha-xs1-development-story.html
There was another article about Yamaha engineers initial disappointment with the engine's low power output and how it was dealt with but I'd lost the text.