Yamaha Genesis 7 Valve per cylinder
While the 7-valve variant of the Genesis engine really wasn’t ever close to production, it is important because it really showed that there is such thing as too much. A leader in multi-valve technology at the time, Yamaha experimented with its Genesis engine program to find out how many valves shoved into a combustion chamber were too many. With four intake valves, three exhaust valves, and two spark plugs per cylinder, the R&D team finally found the wall. In fact, they also tried an experimental six-valve design as well, and found it to perform worse than a five-valve design, setting the standard early on for five-valve-per-cylinder designs.
