Honda CR250M Elsinore

Honda CR250M Elsinore History

The Honda CR250M Elsinore is a two-stroke motorcycle first manufactured by Honda in March 1973; it had 29 horsepower and weighed 229 pounds.[1][2] It was designed by Soichiro Miyakoshi, and prototype testing began in Japan in 1971 and on California motocross tracks in 1972.[3] The CR250M was Honda’s first two-stroke production race bike, the first competition dirt bike that Honda built from scratch instead of adapting a street bike,[4] and the first production motocrosser.[5] A chome-moly frame, aluminum bodywork and plastic fenders contributed to its light weight,[2] even after restyling when initial tests showed the frame to be too fragile, potentially bending after less than an hour of riding.[6]

The Elsinore was named after the offroad race in Lake Elsinore, California,[7] the best-known off-road race of the late 1960s and early 1970s.[2] The popularity of the CR250M and its derivatives soared after Gary Jones rode a stock machine to win the 1973 AMA 250 national motocross series.[2]

In 1974 the CR250M was followed by its ‘son’, the Honda CR125M,[4] and the first US Honda factory that opened in 1979 in Marysville, Ohio built CR250Ms.[8]

Specifications[edit]

Bore and Stroke: 70×64.4mm

Engine: 247.8cc

Transmission: 5-speed

Wheelbase:56.5in

Ground Clearance: 7in

Capacity: 1.5gal

Weight: 213lb (dry)

Top Speed: 75mph[9]

Model Codes[edit]

The 357 was released as a Honda CR250M in the years 1973 and 1974, and the 381 was released as a CR250M1 in 1975 and as a CR250M’76 in 1976.Honda CR250M Elsinore

1-Honda-C100

Honda Super Cub

The Super Cub has been compared to the Ford Model T, Volkswagen Beetle and the Jeep as an icon of 20th century industry and transport.[9][10][19] The C100 used a pressed steel monocoque chassis, with the horizontal engine placed below the central spine, a configuration now called the ‘step through’ or ‘underbone’ motorcycle. By some criteria, the type of motorcycle the Super Cub falls into is difficult to classify, landing somewhere between a scooter and a motorcycle,[16] and sometimes it was called a moped, “step-thru”, or scooterette.[11][20][21]

The instruments of a 1966 CA100 and 2009 Super Cub 110

A plastic fairing ran from below the handlebars and under the footpegs, protecting the rider’s legs from wind and road debris, as well as hiding the engine from view. This design was like the full enclosure of a scooter, but unlike a scooter the engine and gearbox unit was not fixed to the rear axle. This had several benefits. It moved the engine down and away from the seat, detaching the rear swingarm motion from the drivetrain for lower unsprung weight, and also made engine cooling air flow more direct, and it made possible larger wheels.[11] Placing the engine in the center of the frame, rather than close to the rear wheel, gave it proper front-rear balance.[12] The fuel tank was located under the hinged seat, which opened to reveal the fuel filler inlet. The 17 inch wheels, in comparison to the typical 10 inch wheels of a scooter, were more stable, particularly on rough roads, and psychologically made the motorcycle more familiar, having an appearance closer to a bicycle than a small-wheel scooter.[11]

The Super Cub early push-rod engine.

The pushrod overhead valve (OHV) air-cooled four stroke single cylinder engine had a 40-by-39-millimetre (1.6 in × 1.5 in) bore × stroke, displacing 49 cubic centimetres (3.0 cu in), and could produce 3.4 kilowatts (4.5 hp) @ 9,500 rpm, for maximum speed of 69 km/h (43 mph), under favorable conditions.[22] The low compression ratio meant the engine could consume inexpensive and commonly available low octane fuel, as well as minimizing the effort to kick start the engine, making the extra weight and expense of an electric starter an unnecessary creature comfort.[22] Though some of the many Super Cub variations came with both kick and electric start, the majority sold well without it, and even the latest 2011 model year Japanese domestic market (JDM) Super Cub 50 and Super Cub 110 versions, using up to date technology like Honda’s Programmed fuel injection (PGM-FI) and convenience features like a fuel gauge, were not offered with an electric start option.[23][24]

The sequential shifting three speed gearbox was manually shifted, but clutchless, without the need for a clutch lever control, using instead a centrifugal clutch along with a plate clutch slaved to the footchange lever to engage and disengage the gearbox from the engine.[22] While not intuitive to learn, once the rider got used to it, the semi-automatic transmission, “took the terror out of motorcycling” for novice riders.[22] Unlike many scooter CVTs, the centrifugal clutch made it possible to push start the Super Cub, a useful advantage if the need arose.[12]

The early Super Cubs used a 6 volt ignition magneto mounted on the flywheel, with a battery to help maintain power to the lights, while later ones were upgraded to capacitor discharge ignition (CDI) systems. The lubrication system did not use an oil pump or oil filter, but was a primitive splash-fed system for both the crankcase and gearbox, with a non-consumable screen strainer to collected debris in the engine oil. Both the front and rear brakes were drums. On both the front and rear wheels were 2.25″ × 17″ wire spoke wheels,[22][25] with full-width hubs.[11]

Honda recommended daily checks of the lights, horn, tire pressure, brakes, fuel and oil level, and a weekly check of the battery electrolyte level. The new engine break in maintenance was done at 320 kilometres (200 mi), requiring adjustment of the valve tappets and contact breaker points, and an oil change, and the rider was advised to stay under 48 kilometres per hour (30 mph) for the first 800 kilometres (500 mi). Every 1,600 kilometres (1,000 mi) the spark plug needed cleaning, and the chain adjustment checked, and every 3,200 kilometres (2,000 mi) an oil change, breaker point check, and valve adjustment was due. At 8,000 kilometres (5,000 mi), major maintenance was due, requiring the removal and cleaning of the carburetor, drive chain, exhaust silencer, and wheel bearings.[25] The rider closed a manual choke to aid in starting at cold temperatures.[25] By the standards of the day, this was an extremely simple motorcycle, with minimal maintenance demands, and it earned a reputation for high reliability.[17][1-Honda-C100

Kawasaki Z1 Prototype

Kawasaki Z1 Motorcycle History

History[edit]

The Kawasaki Z1 was developed in strict secrecy under the project name “New York Steak”.[8][9] In the late 1960s Kawasaki, already an established manufacturer of two-stroke motorcycles, decided to make a 750 cc four-cylinder four-stroke sports motorcycle[2] (they even had an appearance prototype designed by McFarlane Design in 1969),[11] but they were beaten to the marketplace by the Honda CB750. This postponed the Z1′s release until its displacement could be upped to 903 cc and sold as a 1000cc-class machine.[2]

Production began in 1972; at the time it was the most powerful Japanese 4-cylinder 4-stroke ever built.[6] The Z1 had full instrumentation and an electric start, produced 82 bhp and had a maximum speed of 130 mph (210 km/hr).[5] It met with very positive reviews from the motorcycle press, who praised its smoothness, damped vibration, easy-starting (kick-start and electric were both available), straight-line stability and linear acceleration. Steering was accurate and the bike handled well, but testers said the rear tire, chain and rear shocks all wore out quickly.[2]

The Z1 was awarded the MCN ‘Machine of the Year’ accolade for four years running between 1973 to 1976 (an award resulting from a readers’ opinion-poll run by UK weekly publication Motorcycle News)[12] The Society of Automotive Engineers of Japan (Japanese) includes the 1972 Z1 as one of their 240 Landmarks of Japanese Automotive Technology.[1]

Kawasaki Z1 Prototype
Kawasaki Z1 Prototype