Imagine this: it’s the late 1970s and you’re a Honda engineer working for the man himself, Soichiro Honda. It is a truth, universally recognized, that the Old Man absolutely, unequivocally hated two times. However, he loves to test his company’s engineering mettle in motorcycle racing—and that’s also when two-strokes rule the world. Plus, there’s that little conundrum that most racing series tend to have: a set of rules that must be followed. What are you doing?
If you’re Honda, you get to work designing a new four-stroke, four-cylinder machine. According to the existing regulations, four is the maximum number of cylinders a bike can have, 500cc is the maximum displacement, and the bike must also be naturally aspirated. With two-strokes of the era hovering around the 120-horsepower mark, this is certainly a tough, but impossible, puzzle to solve.
Not if you are completely out of your mind– um, if you’re Honda, we mean. (We’re kidding. The general consensus here is that weird Honda trying new things is the best Honda, and we’ll definitely take interesting failures on boring races any day of the week.) If you’re familiar with the Honda’s oval-piston motorcycles, the NR 500 and later NR 750, this problem is exactly what Honda engineers were trying to solve. (The NR designation, in typical understated Honda fashion, stands for “New Racing.”)
To get a four-stroke, four-cylinder engine that easily produced the kind of power that the two-stroke competition easily generated, Honda had to think differently. Increasing airflow was a must, so engineers started thinking about valves. If you could get more airflow, more combustion, and higher revs, this engine could theoretically generate the kind of power you need. That’s how Honda engineers came up with an eight-valve-per-cylinder design.
Naturally, these eight valves all need space to operate, which is why the piston has become oval. Additionally, the new piston design and expected high revs also required two connecting rods per piston, not to mention a complete redesign of the piston ring design. To sum up a long and incredibly strange story, every problem Honda tackled seemed to lead to a number of other problems, which the team also had to face if they were to successfully create their new racing engine.
The result of all that hard work was the NR 500, which Honda finally raced in 1979. Unfortunately for the team, it didn’t perform as well as they had hoped, only managing to take two wins. racing all season. . Honda ditched the idea until 1992, when it was decided the time was right for a production oval-piston bike. That’s how the NR 750 was born, but at an MSRP of around $60,000, it’s probably not that hard to see why it didn’t exactly roll out of the showrooms. Yet Honda’s unique approach to problem-solving has historically produced some of its most beloved bikes.
Sometimes simplicity is better, but sometimes taking the winding and complicated route to answering a question is much more interesting. Thanks for giving us food for thought, Honda.