The Honda CB750 Four’s technological advances are akin to putting a man on the moon – both of which celebrate a 50th anniversary this year
Fifty years ago, Glenn Turple was riding his motorcycle in central Alberta when he stopped in the small town of Killam for lunch at a diner. Sitting on the counter was a black-and-white television set tuned to the news, and Turple learned that the Apollo 11 mission had successfully landed on the moon. For centuries, humans had dreamed of reaching the lunar surface, and Apollo 11’s accomplishment awed the world.
Just one week later, Turple was riding a brand-new 1969 Honda CB750 Four. The two events are forever linked in his mind – and, not to downplay the importance of landing a man on the moon – and to the motorcycle community, the CB750 was no less a groundbreaking achievement.
“The CB750 was an exciting motorcycle that started the four-cylinder revolution,” Turple explains. “Riding that Honda for the first time was an eye-opening experience.”
And Turple should know. His first motorcycle was a non-running 1926 Harley-Davidson bought in partnership with his late brother, Rex. Turple didn’t help get the Harley-Davidson running and have a turn behind the bars, though, as he left the family farm at Olds, Alta., to work an autumn harvest in Ontario.
“Rex got the bike running while I was away, and by the time I came back it was broken again,” Turple laughs.
A Lifelong Passion Begins
“I got about 3,000 miles on the Panther, about 10,000 on the Ariel and, in 1948, about 8,000 on a 350 cc Triumph,” Turple explains.
In 1949, he bought a brand-new 500 cc Norton ES2 from English Motorcycle Sales in Calgary. He rode that single-cylinder motorcycle for 23,000 miles, including a journey to Los Angeles.
By this time, motorcycles were a passion for the Turple brothers. They set up Olds Motorcycle Sales in a small shed on the family farm. They were a subdealer for Norton through English Motorcycle Sales; for BSA through Fred Deeley Motorcycles in Vancouver; and for Triumph through Nicholson Bros.
The brothers earned money by supplying parts and service and selling new bikes. Glenn Turple bought a 1950 BSA 650 Golden Flash, and the odometer soon read 22,000 miles. He once rode the BSA on a journey to New York, Boston and New Hampshire.
Expansion
But, at a dealer meeting in Calgary in the late 1950s, Glenn Turple was introduced to Japanese motorcycles – specifically, to Honda.
“At a downtown Calgary hotel, Trev Deeley showed off the new BSAs, Triumphs and Ariels,” Turple says. “After discussing the British bikes, Deeley said, ‘I’ve got a surprise for you.’ In another room, he showed us some new Hondas: a step-through 50 and a Dream. We all looked at him funny, and there weren’t many takers.”
However, some dealers, including Bob Kane Sr. of Calgary, did take the little Hondas. To everyone’s surprise, the Japanese motorcycles sold quickly.
Taking on Honda
“That meeting was in the spring of 1959, and we took on the Honda line in August of that year,” Turple says.
Alongside the larger British motorcycles, Turple says, the brothers successfully sold small-bore machines such as the Honda 50 and the Dream in 250 cc and 305 cc sizes, followed by the 250 cc Hawk and the 305 cc Superhawk.
“The British-built 650s were the largest bikes we sold, and people who moved up from a 305 Honda to a 650 Triumph were often disappointed at the maintenance costs of the Triumph compared with the Honda,” Turple says, adding, “and people were also surprised at how the 305 could come close to the 650 for speed.”
Then in 1965, Honda introduced the CB450 with its 43-hp double-overhead cam, twin-cylinder engine. In comparison, a 1966 Triumph Bonneville, with its twin cylinders and twin carburetors, was rated at 47 hp. Turple bought a CB450 in 1966, a motorcycle that he says could outrun and outpull any of the British-built 650s. He toured on the electric-start 450 and put 45,000 miles on the odometer –in fact, that was the bike he rode to Killam when he heard about the moon landing.
Introducing the CB750 Four
There had been other mass-produced four-cylinder motorcycles built in the decades before Honda began producing the CB750, including the Belgian-made inline-four FN and several U.S.-built machines such as the Pierce, Henderson, Militaire, Cleveland, Ace and Indian. Each of these, along with the British-made Vauxhall and Wilkinson, plus the Nimbus from Denmark, had their engines mounted in line with the frame, like the FN did.
Ariel, too, produced a four-cylinder machine, but those four pots were arranged in a square, like two parallel twins mounted fore and aft. Ariel produced the Square Four from 1931 to 1959, and that was the last mass-produced four-cylinder machine until Honda’s CB750 appeared on the scene.
Honda, acquiescing to North American demand in 1967 for a larger, more powerful motorcycle, laid out certain “engineering targets” for the CB750. According to an article about the model on the Global Honda website, these targets included the motorcycle’s ability to remain stable while maintaining speeds between 140 km/h and 160 km/h; a better braking system; less noise and vibration combined with ideal rider ergonomics; reliable lights and instruments; long service life, with ease of maintenance; and efficient use of newer materials and production techniques.
The Bike That Changed Motorcycling
The CB750, as launched in January 1969, featured a transverse-mounted 67-hp, 736 cc SOHC four-cylinder engine with electric start. Fuel and air mixed in a set of four 28-mm Keihin carburetors, and spent gases were expelled through an unmistakable set of four-into-four header pipes and mufflers. The CB750 also was the first mass-produced machine with a front disc brake.
The first of the CB750 K0 machines were dubbed “sandcast” models simply because the casting technique used to produce the engine cases left a rough finish. After Honda realized it had a winner on its hands, it quickly changed its engine case-casting methods.
Turple’s 1969 CB750 bears the frame number CB7501000972 and, he says, the engine number is slightly above 1,000. This puts the bike early in the run of sandcast models. Many sources state the last sandcast-engine number is 7414.
“[The 1969 CB750] was a tremendous motorcycle, and it severely outperformed the competition,” Turple recalls. “There was so much more horsepower available, and the 750 would rev higher and take sustained revs without vibrating apart. And I’d wondered why a disc brake would be a big deal. But after my first ride, I knew. It was such a better brake than any of the drum brakes I’d had on my previous bikes.”
The Making of a Touring Bike
Shortly after Turple got his CB750 in September of 1969, he added a handlebar-mounted windshield and soft saddlebags, then rode to San Diego, Calif. Accessory manufacturers took some time to introduce products to fit the Honda, but when Wixom launched a fairing, hard saddlebags and top case package, Turple added them to his CB750.
“[Touring is] so much more relaxing when you’re not pushing that air with your body,” he says about his reason for fitting the fairing and bags.
Of the CB750’s ability to handle, Turple says, “They weren’t race bikes; there were other bikes that could handle better. But for long-distance touring, the CB750s were great. They were all about performance and overall reliability.”
Turple explains it this way: after he rode a Triumph 650 for some 9,000 miles, the engine had to come apart and the cylinders showed .011” of wear. On his CB450, at 45,000 miles the cylinders showed some .006” of wear. On his CB750, however, when it was pulled apart at 103,000 miles, the cylinders showed only .002” of wear.
“That was remarkable to get that kind of longevity,” Turple says.
Not All 750s are the Same
After the K0 of 1969, in 1971 Honda brought out the CB750 K1. These first two generations of the CB750 are known among Honda enthusiasts as “the performance models,” as they featured larger jets in the carbs and a less restrictive exhaust system. Also, the spark-advance mechanism was a quick advance unit – meaning full advance was happening at 2,000 rpm. These machines produced about 67 hp at the rear wheel.
In 1972, Honda detuned the CB750 engine when the K2 model was introduced. The cam was changed, the jets were smaller and a five-chamber baffled muffler was employed. Horsepower at the rear wheel dropped to 58 from 67. Chrome fork ears and a seat lock were added.
By 1973, when Honda introduced the K3 – which had an even more restrictive muffler, new style gauge mounts, a disc brake splash guard and a broad stripe down each side of the gas tank, much of the lustre had worn off of the CB lineup. And other Japanese motorcycle makers hadn’t taken very long to catch up. In 1971, Suzuki brought out its two-stroke liquid-cooled triple-cylinder GT750,; in 1973, Kawasaki delivered its Z1 900 four-cylinder motorcycle. The “superbike” era of Japanese machinery got hot fast.
Although Honda introduced the CB750 K4 in 1974 and the CB750 K5 in 1975, there were no major changes to the CB750 lineup in those two years, apart from colour options. Honda had further detuned the 736 cc powerplant to help increase fuel efficiency, but this resulted in approximately 38 ponies at the rear wheel.
A More Powerful Super Sport
Honda lost much of the performance market the company had created and, as a result, developed the 1975 CB750F Super Sport. In reality, this machine wasn’t radically changed from the K-series. The new model featured a new chassis with shorter trail; lengthened rear swingarm with a rear disc brake; a four-into-one header and muffler system; a longer gas tank; and a new seat, complete with a cowl. The engine was given back some of its initial oomph, and horsepower increased to 58 – the same state of tune found in the earlier CB750 K2.
The CB750 K6 of 1976 was the last of the “classically” styled Honda CBs. That year was the final one for the slightly bulbous gas tank and the rounded, pleasantly shaped side covers. Only one colour, Candy Antares Red, was available.
The CB750 carried on with a cosmetically redesigned K7 and K8 model in 1977 and 1978, respectively, both with a large and angular fuel tank and different frame and forks. Honda also continued with the CB750 F Super Sport, and the 1977 and 1978 Super Sport engines had increased power, thanks to larger intake valves, higher compression ratios, different high-lift cams and revised carbs. These latter bikes are commonly referred to as “black-engine bikes,” thanks to the black finish on external engine components.
Another note to the CB saga is the 1976 Honda CB750A – a mass-produced automatic-shift motorcycle that while much loved by those who bought them and those who continue to ride them, never became a commercial success. The CB750A was discontinued after the 1978 model year.
Then, in 1979, Honda replaced the SOHC engine with a DOHC engine, and the models so equipped include the CB750 Custom and CB750 Nighthawk.
Still a Treasured Stablemate
Turple rode his sandcast CB750 exclusively from 1969 to 1975, including several trips to California and one to Mexico. When the original odometer reached 99,999 miles, he added a second instrument instead of allowing the first to simply roll over. This is a common tactic used by those who enjoy logging the mileage on their long-term motorcycles.
When Honda launched the GL1000 Gold Wing in 1975, Glenn made the switch to the larger touring machine. He then rode the CB750 only occasionally, but it remains in his stable of favoured machines and is, in his estimation, as important as putting a man on the moon.
