This is a rare “Sandcast” 1969 Honda CB750 “Sandcast” that’s historically significant for two reasons, firstly it was the world’s first “superbike” and secondly it was bought new by Steve McQueen through his production company Solar Productions.

For those who may not know about this 500 pounds of Iconic Motorcycling Mastery, here is a small run down of the inline four Japanese History.

Having captured five consecutive championship titles in the historic 1966 World Grand Prix Road Racing Series, Honda decided to withdraw from the World GP circuit beginning the very next season. Upon that announcement, the company turned toward its primary target; the development of high-performance consumer machines. Thus it would achieve through the application of technology obtained in road racing.

Honda was in those days exporting more than half of its Japanese-made motorcycles. The company, however, did not offer large-displacement sports bikes, even though they were in great demand in developed countries such as the U.S. Moreover, sales of Honda motorcycles in America had begun to drop in 1966. Accordingly, American Honda had been asking for the development of new products.

The Dream CB450 was released in 1965 as a high-performance bike. Featuring a two-cylinder DOHC engine, it had been created at the request of American Honda, which wanted a higher-class version of its predecessor, the 305 cc CB77. Yoshiro Harada, who was in charge of the development project, reflected on the product’s history.

“In 1960,” he recalled, “the U.S. market for large motorcycles was approximately 60,000 units annually. Of these, most were imports from British makers. The Japanese market was comparatively much smaller, with monthly sales of several hundred units. But through our understanding of the situation we decided to develop a 450-cc bike, specifically a mass-production model, that could be sold in the U.S. as well as Japan.”

The CB450 sold relatively well, but it did not win acceptance as a major product. The majority of American riders, it seemed, did not judge motorcycles simply by how fast they could go. They also wanted responsive torque performance so that they could get the power they needed without downshifting. For many local riders, motorcycles represented a means of recreation and relaxation rather than rocket-sled performance.

Harada visited the U.S. around the summer of 1967 to observe the CB450’s impact in local markets. He even went so far as to detail the machine’s superior performance to the staff at American Honda, telling them it was even better than the 650 cc models by Norton and Triumph. However, they did not see the point in riding a 450 cc bike. Instead, they simply held to the belief that “bigger was better.”

The 650 cc displacement size was the largest to be found in Japan, yet these bikes accounted for only a few percentage points in the overall market. Harada therefore decided to develop a bigger model, as an obvious nod to the U.S. market. However, the request given by American Honda, ‘”the bigger the better,” seemed quite vague to him. Based on that advice alone, it would be difficult for Harada to determine the right displacement.

It was then that Harada learned from a reliable source that Britain’s Triumph was developing a high-performance model with a 3-cylinder 750 cc engine. This bit of news determined the engine specification. By October 1967, the outline for Honda’s new larger cc model had been defined: it would be driven by a 750 cc engine having a maximum output of 67 horsepower (one more than Harley-Davidson’s 1300 cc unit, whose maximum output was 66 horsepower).

A team of about twenty members was assembled on behalf of the development project in February 1968. The design of the CB750 FOUR had officially begun. However, Honda was already the industry’s leading producer of motorcycles, thanks to the popularity of its classic Super Cub. By introducing the CB750 FOUR, the company planned to become the world’s top manufacturer in terms of quality as well as volume. This model’s competition, however, would be formidable, since the pack included comparable models from Triumph, BMW, and Harley. Therefore, the new Honda would have to offer a superior level of performance and reliability in order to lead the field.

A 4-cylinder, four-muffler engine structure was to be the basis for design so that riders in every market could immediately associate the bike with the stunning performance of Grand Prix machines. Moreover, the handlebar position would be elevated – popular among American riders – to emphasize the bike’s dynamic, “wild” image. As Honda’s first mass-production model with a large powerplant, the CB750 employed various technologies designed to ensure high production volume and easier maintenance for the owner.

Integrating Design with Human Engineering

The objective of Honda’s basic development plan was to make long-range, high-speed touring safer and more comfortable, while achieving superior output. Therefore, the emerging science of human engineering – called “ergonomics” – was to be incorporated structurally, right down to the finest detail.

To facilitate the collaborative process among design engineers and production personnel, common engineering targets were established for product development. These included the following:

[1] Ensure stability during high-speed cruising (between 140 and 160 km/h) on highways, yet retain an ample margin of output for effective maneuvering in traffic.
[2] Provide a braking system that is reliable and resistant to high loads by anticipating frequent rapid decelerations from high speeds.
[3] Minimize vibration and noise in order to reduce rider fatigue during long-range cruising. Provide an ideal riding position for comfort and the proper operation of controls based on human-engineering principles, and design the mechanisms so that the rider can easily learn how to operate them.
[4] Ensure that various ancillary devices, such as lights and instruments, are large and reliable. They must be designed to help the rider make sound judgments and ensure sufficient visibility for surrounding vehicles.
[5] Extend the service life for each device and ensure that it provides for easy maintenance and servicing.
[6] Create original designs that also are easy to mass produce by utilizing newer, better materials and production technologies. This applies particularly to cutting-edge surface-treatment technologies.

The satisfaction of these requirements meant that the team would have to utilize the vast reserves of engineering information Honda had accrued in the manufacture of Grand Prix machines. Moreover, computer systems would be introduced in order to streamline the various steps involved in development. However, computerization ultimately did more than that. It increased the efficiency of numerous development tasks, including plan modification in the prototype phase, design changes, hardware modifications, and testing. It even reduced the time needed to plan a line for mass production of the CB750 FOUR.