Honda CB750

Honda CB750
Manufacturer Honda
Production 1969–2003, 2007
Class Sport bike or standard
Engine SOHC air-cooled straight four (1969-1978)
DOHC air-cooled straight 4 (1979–2003, 2007)
Top speed 125 mph (201 km/h)
Power

68 hp (51 kW) @ 8,500 rpm (1969) [1]

67 hp (50 kW) @ 8,000 rpm(DIN),[2] [3]
Torque 44 ft·lbf (60 N·m) @ 7,000 rpm
Transmission 5-speed
Suspension Front: telescopic forks
Rear: swingarm with two spring/shock units.
Brakes Front disc / Rear drum
Tires Front: 3.25" x 19"
Rear: 4.00" x 18"
Rake, Trail 3.7 in (94 mm)
Wheelbase 57.3 in (1,460 mm)
Dimensions L 85 in (2,200 mm)
W 35 in (890 mm)
H 44 in (1,100 mm)
Seat height 31 in (790 mm)
Weight 491 lb (223 kg) (wet)
Fuel capacity 4.7 US gal (18 l; 3.9 imp gal)

The Honda CB750 is a motorcycle built in several model series between 1969 and 2003 and 2007 that is recognized as a milestone for Honda's successful introduction of a transverse, overhead camshaft inline four-cylinder engine that has ever since been the dominant sport bike configuration. Though MV Agusta had sold such a model in 1965, and it had been used in racing engines before World War II, the CB750 is recognized as the four-cylinder sport bike that had a lasting impact and is often called the first superbike.[4][5] The model is included in the AMA Hall of Fame Classic Bikes,[6][7] the Discovery Channel's "Greatest Motorbikes Ever,"[8] and was in The Art of the Motorcycle exhibition,[4] and is in the UK National Motor Museum.[9]

Contents

History

Honda of Japan introduced the CB750 motorcycle to the US and European markets in 1969 after experiencing success with their smaller motorcycles. The bike was targeted directly at the US market after Honda officials, including founder Soichiro Honda, repeatedly met with US dealers and understood the opportunity for a larger bike.[10]

Under development for a year,[11] the CB750 offered two unprecedented features, a front disc brake and a transverse straight-4 engine with an overhead camshaft, neither of which was previously available on a mainstream, affordable production bike. These two features, along with the introductory price of US$1,495[12] (US$8,956 in current money), gave the CB750 a considerable advantage over its competition, particularly its British rivals.

Cycle magazine called the CB750 "the most sophisticated production bike ever" upon its introduction.[12] 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 performance of the braking, the comfortable ride and excellent instrumentation.[11]

The CB750 was the first modern four-cylinder machine from a mainstream manufacturer,[13] and the term superbike was coined to describe it.[7][3] The bike offered other important features that added to its compelling value: electric starter, kill switch, dual mirrors, flashing turn signals, easily maintained valves and overall smoothness and freedom from vibration both underway and at a standstill; later models (1991 on) included maintenance-free hydraulic valves. On the other hand, the bike was difficult to get on its center stand and tended to throw chain oil onto its muffler.

Unable to gauge demand for the new bike accurately, 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 lineup for ten years, with sales totaling over 400,000 in its life span.[14]

The CB750 is sometimes referred to as a Universal Japanese Motorcycle or UJM.[3][15] The Discovery Channel ranked the Honda CB750 third among the top ten greatest motorbikes of all time.[8]

Models

SOHC

The single overhead cam models were produced from 1969 through 1978.[16]

DOHC

CB750A Hondamatic

CB750A
Also called Hondamatic
Production 1976–1978[18]
Engine 736.6 cc (44.95 cu in) inline-four, SOHC air-cooled
Bore / Stroke 61 × 63 mm (2.4 × 2.5 in)
Compression ratio 7.7:1
Power 47 hp (35 kW) @ 7,500 rpm[18]
Torque 5.0 kg·m (49 N·m; 36 ft·lbf) @ 6,000 rpm[18]
Ignition type Coil
Transmission Two speed, w/torque converter, chain
Brakes Front: 296 mm (11.7 in) disc
Rear: 180 mm (7.1 in) drum
Tires Front: 3.5" x 19"
Rear: 4.5" x 17"
Wheelbase 58.1 in (1,480 mm)
Dimensions L 89.0 in (2,260 mm)
W 33.7 in (860 mm)
Fuel capacity 18 l (4.0 imp gal; 4.8 US gal)

In 1976, Honda introduced the CB750A to the United States, the A suffix implying "automatic." Although the two-speed transmission included a torque converter typical of an automatic transmission, the transmission did not automatically change gears for the rider. Each gear was selected by a foot-controlled hydraulic valve/selector (similar in operation as a manual transmission motorcycle).[18][19] The foot selector controlled 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 would remain selected until changed by the rider, or the kickstand was lowered (which shifted the transmission to neutral).[20]

The CB750A was sold in the North American market only.[19] 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,[20][21] a kei car sold in Japan from 1967 to 1972.

The CB750A used the same engine as the CB750, but detuned with lower 7.7:1 compression and smaller carburetors producing a lower output, 47.0 hp (35.0 kW). The same oil was used for both the engine and transmission, and the engine was changed to a wet sump instead of dry sump type. A lockout safety device prevented the transmission from moving out of neutral if the side stand was down. There was no tachometer but the instruments did 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,[18] though Honda did later introduce smaller Hondamatic motorcycles (namely the CB400A, CM400A, and CM450A).

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 as the CB750SC Nighthawk while later models were simply known as the Nighthawk 750.[22][23] The Nighthawk 750 features a 4-stroke engine with a 5-speed manual transmission, and has front disc and rear drum brakes.

2007 CB750

In 2007, Honda Japan announced the sale of a new CB750 very similar to the models sold in the 1970s. Announced as the CB 750 Special Edition which is in the silver colors of the CB 50 AMA racer of the 1970s, and the CB750, offered in three color schemes reminiscent of CB750s sold previously. As of August 2007, these bikes have only been announced for the Japan domestic market.[24]

Specifications

Model Engine displacement Fuel system Cam Valves per cylinder Power Torque Weight Drive
1969 CB750 Four [25] [26] 736 cc (44.9 cu in) [26] 4 carburetors [26] SOHC [26] 2 67 bhp (50 kW) @ 8,000 rpm [26] [4] [27] 59.8 Nm (44.12 ft·lbf) @ 7,000 rpm [26] 218 kilograms (480 lb) [26] 5 Speed, Constant Mesh, Gearbox, Final Drive Chain [26]
1976–1978 CB750A [28] 736 cc (44.9 cu in) 4 carburetors SOHC 2 47 hp (35 kW) @ 7,500 rpm [18] 5.0 kg·m (49 N·m; 36 ft·lbf) @ 6,000 rpm [18] 262 kg (580 lb) [28] Two-speed w/torque converter, chain[18]
1978 CB750K12 [29] 748 cc (45.6 cu in) 4 carburetors DOHC 4 65 hp (48 kW) @ 9000 RPM 5.9 kg·m (58 N·m; 43 ft·lbf) @ 7000 RPM 231 kg (510 lb) Dry 5 Speed, Constant Mesh, Gearbox, Final Drive Chain
1979-1980 CB750F (RC04) [30] 748 cc (45.6 cu in) 4 carburetors [30] DOHC [30] 4 68 hp (51 kW) @ 9000 RPM [30] 5.9 kg·m (58 N·m; 43 ft·lbf) @ 8000 RPM[30] 228 kg (500 lb) Dry [30] 5 Speed, Constant Mesh, Gearbox, Final Drive Chain [30]
1980–1982 CB750C Custom[31] 748 cc (45.6 cu in) 4 carburetors [31] DOHC [31] 4 65 hp (48 kW) @9000 RPM [31] 5.9 kg·m (58 N·m; 43 ft·lbf) @ 7000 RPM [31] 236 kg (520 lb) dry
[31] ~252 kg (560 lb) wet[31]		 5 Speed, Constant Mesh, Gearbox, Final Drive Chain [31]
1981 CB750F 748 cc (45.6 cu in) 4 carburetors DOHC 4 70 hp (52 kW) 536 lb (243 kg) Chain
1982–1983 CB750SC (Nighthawk) 749 cc (45.7 cu in) 4 carburetors DOHC 4 66.57 hp (49.64 kW) @ 9,000 rpm 41.54 ft·lbf (56.32 N·m) @ 7,500 rpm 573.5 lb (260.1 kg) wet 5-speed, chain[32][33] See also Honda CB700SC
1991–1993, 1995–2003 CB750 (Nighthawk) 747 cc (45.6 cu in) 4 Keihin 34 mm Constant Vacuum carburetors DOHC 4 75 hp (56 kW) @ 8,500 rpm 64 N·m (47 ft·lbf) @ 7,500 rpm 463 lb (210 kg) Chain
2007 CB750 747 cc (45.6 cu in) VENAC DOHC 4 74 hp (55 kW) @ 8,500 rpm[34] 64 N·m (47 ft·lbf) @ 7,500 rpm[34] 520 lb (240 kg)[34] Chain

References

  1. ^ Honda CB750 – It Really Changed Everything, by Paul Crowe - "The Kneeslider" on 5/1/2008.
  2. ^ 240 Landmarks of Japanese Automotive History,.
  3. ^ a b c Walker, Mick (2006), Motorcycle: Evolution, Design, Passion, JHU Press, p. 150, ISBN 0801885302, http://books.google.com/?id=AHSlknpjrgAC&pg=PA150 
  4. ^ a b c Statnekov, Daniel K.; Guggenheim Museum Staff (2003), "Honda CB750 Four", in Krens; Drutt, The Art of the Motorcycle, Harry N. Abrams, ISBN 0810969122, http://books.google.com/?id=unkLAAAACAAJ 
  5. ^ Landon Hall (July/August 20069). "Honda CB750 Four: A Classic for the Masses". Motorcycle Classics. http://www.motorcycleclassics.com/motorcycle-reviews/2006-07-01/classic-for-the-masses-honda-cb750.aspx. Retrieved 2010-11-17. 
  6. ^ Motorcycle Hall of Fame, 1969 Honda CB750; The Year of the Super-bike, American Motorcyclist Association, http://www.motorcyclemuseum.org/classics/bike.asp?id=91 
  7. ^ a b "The Dawn of the Superbike: Honda's Remarkable CB750", AMA Motorcycle Hall of Fame (American Motorcyclist Association), http://www.motorcyclemuseum.org/exhibits/superbikes/CB750/CB750.asp, retrieved 2010-02-20 
  8. ^ a b "Greatest Motorbikes Ever". Discovery Channel. http://www.discoverychannel.co.uk/greatest_ever/motorbikes/index.shtml. 
  9. ^ List of vehicles, National Motor Museum Trust, http://www.nationalmotormuseum.org.uk/?location_id=335, retrieved 2010-01-19 
  10. ^ Honda. "The Dream CB750 Four (Official history)". http://world.honda.com/history/challenge/1969cb750four/index.html. 
  11. ^ a b "Honda's Fabulous 750 Four; Honda Launches the Ultimate Weapon in One-Upmanship — a magnificent, Musclebound, Racer for the Road", Cycle World: 36–39, January 1969, ISSN 0011-4286 
  12. ^ a b "Cycle Road Test: Honda 750cc Four", Cycle (magazine): 33–39, 78–81, August 1969 
  13. ^ Wilson, H. (1995), The Encyclopedia of the Motorcycle, Dorling Kindersley Limited, pp. 88–89, ISBN 0-7513-0206-6 
  14. ^ Alexander, Jeffrey W. (2009), Japan's Motorcycle Wars: An Industry History, UBC Press, p. 206, ISBN 0774814543, http://books.google.com/books?id=Q473NKddjnAC&pg=PA206, retrieved 2011-04-05 
  15. ^ Frank, Aaron (2003), Honda Motorcycles, MotorBooks/MBI Publishing Company, p. 92, ISBN 0760310777, http://books.google.com/?id=CSxTaoGagKoC&pg=PA92, retrieved 2010-02-20 
  16. ^ Mick Duckworth (June 2004), "Classic Bike Dossier: Honda CB750" (PDF), Classic Bike, http://www.classicbike.co.uk/pdf/506/197883.pdf, retrieved 2008-01-15. 
  17. ^ Richard Backus (May/June 2010). "Honda CB750F Super Sport". Motorcycle Classics. http://www.motorcycleclassics.com/motorcycle-reviews/honda-cb750f-super-sport.aspx. Retrieved 2010-05-21. 
  18. ^ a b c d e f g h Bacon, 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&ndsah;112, 185, 192, ISBN 1855790289 
  19. ^ a b Ker, Rod (2007), Classic Japanese Motorcycle Guide, Sparkford, UK: Haynes Publishing, p. 81, ISBN 184425335X 
  20. ^ a b Cycle World, September 1976
  21. ^ The Hondamatic Transmission, The Innovative Automatic Transmission: A Breakthrough in Original Thinking, 1968
  22. ^ Motorcycle Online Frugal Flyers Shootout
  23. ^ Motorcycle Online 2000 Valuebike Shootout
  24. ^ Honda Japan website
  25. ^ Honda Press 18 July 1969, Honda Dream 18 July 1969 CB750 FOUR.
  26. ^ a b c d e f g h Honda Dream CB750 Four History, The First Motorcycle to Offer Disc Brakes.
  27. ^ Brown, Roland (2005), The ultimate history of fast motorcycles, Bath, England: Parragon, pp. 114–115, ISBN 1405454660 
  28. ^ a b [//www.honda.co.jp/news/1977/2770421.html Honda Press 1977], Honda EARA.
  29. ^ Honda Press Dec 1978, 1978 Honda CB750K.
  30. ^ a b c d e f g Honda Press June 1979, 1979 Honda CB750F Released June 23, 1979.
  31. ^ a b c d e f g h Honda Press May 20, 1980, 1980 Honda CB750C, CB750K, CB750F Press Release.
  32. ^ American Honda Motor Company (2000), Honda Motorcycle Identification Guide, 1959-2000, pp. 254–255, 262–263, 278, ISBN 0-9642491-1-1 
  33. ^ Falloon, Ian (2005), The Honda Story: Road and Racing Motorcycles from 1948 to the Present Day, Sparkford: Haynes, pp. 79–82, ISBN 1-85960-966-X 
  34. ^ a b c "Honda CB750 Specifications" (in JP). Honda Japan. http://www.honda.co.jp/motor-lineup/cb750/spec/?from=rcount. Retrieved 9 May 2010. 

External links

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