Though other manufacturers had marketed the transverse, overhead camshaft, inline four-cylinder engine configuration and the layout had been used in racing engines prior to World War II, Honda popularized the configuration with the CB750, and the layout subsequently became the dominant sport bike engine layout.
Honda of Japan introduced the CB750 motorcycle to the US and European markets in 1969 after experiencing success with its smaller motorcycles. In the late 1960s Honda motorcycles were, overall, the world's biggest sellers. There were the C100 Cub step-through—the best-selling motorcycle of all time—the C71, C72, C77 and CA77/8 Dreams; and the CB72/77 Super Hawks/Sports. A taste of what was ahead came with the introduction of the revolutionary CB450 DOHC twin-cylinder machine in 1966. Profits from these production bikes financed the successful racing machines of the 1960s, and lessons learned from racing were applied to the CB750. The CB750 was targeted directly at the US market after Honda officials, including founder Soichiro Honda, repeatedly met US dealers and understood the opportunity for a larger bike.
In 1967 American Honda's service manager Bob Hansen flew to Japan and discussed with Soichiro Honda the possibility of using Grand Prix technology in bikes prepared for American motorcycle events. American racing's governing body, the AMA, had rules that allowed racing by production machines only, and restricted overhead-valve engines to 500 cc whilst allowing the side-valve Harley Davidsons to compete with 750 cc engines. Honda knew that what won on the race track today, sold in the show rooms tomorrow, and a large engine capacity road machine would have to be built to compete with the Harley Davidson and Triumph twin-cylinder machines.
Hansen told Soichiro Honda that he should build a 'King of Motorcycles' and the CB750 appeared at the Tokyo Show in November, 1968 and was publicly launched in UK at the Brighton, England motorcycle show held at the Metropole Hotel exhibition centre during April 1969, with an earlier press-launch at Honda's London headquarters, the pre-production versions appearing with a high and very wide handlebar intended for the US market.
The AMA Competition Committee recognised the need for more variation of racing motorcycle and changed the rules from 1970, by standardizing a full 750 cc displacement for all engines regardless of valve location or number of cylinders, enabling Triumph and BSA to field their 750 cc triples instead of the 500 cc Triumph Daytona twins.
Dick Mann's Daytona-winning CR750 on display at Le Musée Auto Moto Vélo, a transportation Museum in Châtellerault, France
The Honda factory responded by producing four works-racer CR750s, a racing version of the production CB750, ridden by UK-based Ralph Bryans, Tommy Robb and Bill Smith under the supervision of Mr Nakamura, and a fourth machine under Hansen ridden by Dick Mann. The three Japanese-prepared machines all failed during the race with Mann just holding on to win by a few seconds with a failing engine.
Hansen's race team's historic victory at the March, 1970 Daytona 200 with Dick Mann riding a tall-geared CR750 to victory preceded the June, 1970 Isle of Man TT races when two 'official' Honda CB750s were entered, again ridden by Irishman Tommy Robb partnered in the team by experienced English racer John Cooper. The machines were entered into the 750 cc Production Class, a category for road-based machines allowing a limited number of strictly-controlled modifications. They finished in eighth and ninth places. Cooper was interviewed in UK monthly magazine Motorcycle Mechanics, stating both riders were unhappy with their poor-handling Hondas, and that he would not ride in the next year's race "unless the bikes have been greatly improved".
In 1973, Japanese rider Morio Sumiya finished in sixth place in the Daytona 200-Mile race on a factory 750.
Production and reception
Under development for a year, the CB750 had a transverse, straight-four engine with a single overhead camshaft (SOHC) and a front disc brake, neither of which was previously available on a mainstream, affordable, production motorcycle. Having a four-cylinder engine and disc brake, along with the introductory price of US$1,495 (US$10,214 in current money), gave the CB750 a considerable sporting performance advantage over its competition, particularly its British rivals.
Cycle magazine called the CB750, "the most sophisticated production bike ever", on the bike's introduction.Cycle World called it a masterpiece, highlighting Honda's painstaking durability testing, the bike's 120 mph (190 km/h) top speed, the fade-free braking, the comfortable ride, and excellent instrumentation.
The CB750 was the first modern four-cylinder machine from a mainstream manufacturer, and the term superbike was coined to describe it. Adding to the bike's value were its electric starter, kill switch, dual mirrors, flashing turn signals, easily maintained valves, and overall smoothness and low vibration both under way and at a standstill. Much-later models from 1991 included maintenance-free hydraulic valves.
Unable to accurately gauge demand for the new bike, Honda limited its initial investment in the production dies for the CB750 by using a technique called permanent mold casting (often erroneously referred to as sandcasting) rather than diecasting for the engines – unsure of the bike's reception. The bike remained in the Honda line up for ten years, with a production total over 400,000.
Annual and cumulative production statistics, separated by SOHC (to 1978) and DOHC (1979 and later)
Note: All CB750 engines are air/oil-cooled, as opposed to liquid-cooled
1969 CB750 (6 June), CB750K or CB750K0 (date unknown)
1970 CB750K1 (21 September)
1972 CB750K2 (US 1 March)
1973 CB750K3 (US-only 1 February. K2 elsewhere)
1974 CB750K4 (US/Japan-only, K2 elsewhere)
1975 CB750K5 (US-only, K2/K4 elsewhere), CB750FO, CB750A (Canada-only) The 1975 CB750F had a more streamlined look, thanks in part to a 4-into-1 exhaust and cafe style seat with fiberglass rear. Other changes included the use of a rear disc brake and a lighter crankshaft and flywheel.
In 1976, Honda introduced the CB750A to the United States, with the A suffix designating "automatic," for its automatic transmission. Although the two-speed transmission includes a torque converter typical of an automatic transmission, the transmission does not automatically change gears for the rider. Each gear is selected by a foot-controlled hydraulic valve/selector (similar in operation to a manual transmission motorcycle). The foot selector controls the application of high pressure oil to a single clutch pack (one clutch for each gear), causing the selected clutch (and gear) to engage. The selected gear remains selected until changed by the rider, or the kickstand is lowered (which shifts the transmission to neutral).
The CB750A was sold in the North American and Japanese markets only. The name Hondamatic was shared with Honda cars of the 1970s, but the motorcycle transmission was not fully automatic. The design of the transmission is similar in concept to the transmission in Honda's N360AT, a kei car sold in Japan from 1967 to 1972.
The CB750A uses the same engine as the CB750, but detuned with lower 7.7:1 compression and smaller carburetors producing a lower output, 35.0 kW (47.0 hp). The same oil is used for the engine and transmission, and the engine was changed to a wet sump instead of dry sump type. A lockout safety device prevents the transmission from moving out of neutral if the side stand is down. There is no tachometer but the instruments include a fuel gauge and gear indicator. For 1977 the gearing was revised, and the exhaust changed to a four-into-two with a silencer on either side. Due to slow sales the model was discontinued in 1978, though Honda did later introduce smaller Hondamatic motorcycles (namely the CB400A, CM400A, and CM450A).Cycle World tested the 1976 CB750A's top speed at 156 km/h (97 mph), with a 0 to 60 mph (0 to 97 km/h) time of 10.0 seconds and a standing 0 to 1⁄4 mile (0.00 to 0.40 km) time of 15.90 seconds at 138.95 km/h (86.34 mph). Braking from 60 to 0 mph (97 to 0 km/h) was 39 m (129 ft).
1992 Honda Nighthawk 750
From 1982 through 2003, with the exception of several years, Honda produced a CB750 known as the Nighthawk 750. Early models were designated the CB750SC Nighthawk while later models were simply known as the Nighthawk 750. The Nighthawk 750SC had a 4-stroke engine with a 5-speed manual transmission, chain drive, and front disc and rear drum brakes.
2007 Honda CB750 Special
In 2007 Honda Japan announced the sale of a new CB750 very similar to the models sold in the 1970s. Announced as the CB750 Special Edition that was in the silver colors of the CB750 AMA racer of the 1970s and the CB750, it was offered in three color schemes reminiscent of CB750s previously sold. As of August 2007[update], these bikes were intended only for release in Japan.
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^ abcdefg"Honda Dream CB750". 240 Landmarks of Japanese Automotive Technology. Society of Automotive Engineers of Japan, Inc. Archived from the original on 3 November 2013. Retrieved 11 August 2013. Developed with the goal of giving riders greater power with better safety, the Dream CB750 featured Honda's first double cradle frame and the world's first hydraulic front disc brakes.
^ abcdMotorcycle Sport, UK monthly magazine, April 1969, pp. Cover, 121, 132–133. Honda's 750-4 arrives. "The wide, sweeping handlebars on the machines shown at Brighton are fitted in the US market, but before deciding on whether or not these will be the ones for this country some discussion will take place between Honda UK and dealers and prospective owners". Accessed 15 June 2015
^ abMotorcycle Mechanics, May 1969, Showtime - 6-page-special. pp. Cover, 38–39, Honda's Four. "MM takes a close look at the new 4-pot Honda 750". Accessed 15 June 2015
^Original Honda CB750 by John Wyatt - Bay View Books Ltd 1998
^Classic Bike Glamorous and Glorious by Mick Duckworth June 2004 issue
^ abcdefgBacon, Roy (1996), Honda: The Early Classic Motorcycles : All the Singles, Twins and Fours, Including Production Racers and Gold Wing-1947 to 1977, Niton Publishing, pp. 110, 112, 185, 192, ISBN1-85579-028-9