1970s Superbike Shootout

For motorcyclists the 1970s was a special decade; Honda’s launch of the CB750 in 1969 started a race for power and prestige among motorcycle manufacturers worldwide. While Japanese producers manufacturers led the power race, Italian competition offered exquisite engineering and fine handling. Meanwhile, embattled British manufacturers struggled for survival.

In 1970, the US magazine Cycle published their Superbike Comparison Test, the first head-to-head test of the most desirable machines. Seven manufacturers submitted one bike from their 1969 range, which were tested at Orange County International Raceway, near Los Angeles. The line-up included BSA, Triumph, Harley-Davidson, Honda, Kawasaki, Norton and Suzuki. No overall winner was declared, but the Norton Commando S posted the fastest quarter-mile time. The Harley-Davidson XLCH Sportster was disqualified for cheating, having been supplied with oversize inlet ports, valves and a racing oil pump. In response, Harley-Davidson withdrew all advertising from Cycle while Norton dominated the inside cover page with a full-color spread.

By 1973, rapid development and the introduction of significant new models led Cycle to repeat the process. BSA had gone into bankruptcy and Suzuki was no longer a contender. Seven bikes were tested over a six-week period, this time with points awarded for each category. The overall winner – by the smallest margin – was the Kawasaki 750 H2, over the newly-released Kawasaki 900 Z1. Surprisingly, the fifth-placed Ducati 750GT was voted “the bike everyone wanted to ride home”.

Six of the contenders from the 1970 and 1973 tests are displayed here.

CLICK THE NAMES BELOW TO READ MORE

+ 1971 Kawasaki H-1 500 Mach III

Kawasaki Heavy Industries made aircrafts, trains, and industrial equipment and in the 1960’s imported several small displacement twin cylinder 2 cycle motorcycles into the USA. While Kawasaki’s first bike over 500cc was a 4 cycle 650 twin with modest performance and with a new multi cylinder 4 stroke in the works, their H-1 500cc 2 stroke released in 1969 became the most extreme bike on the market. With 60 horsepower on tap and a curb weight under 400lbs, this bike was capable of 1/4-mile times only seen in purpose built drag racers. A three-cylinder, piston port inline engine featured 3 28mm carburetors and capacitor discharge ignition, a first for a multi cylinder motor, but which proved unreliable in early models. Replaced by points ignition in ‘72, Kawasaki returned with an improved CDI ignition in ‘73 and later models.

With a purchase price of under $1000, the H1 became very popular with young men who praised its raw acceleration and light weight but became critical of its poor handling and tendency to wheelie. New riders were often caught unaware when the engine’s abrupt power curve engaged with little warning at 5000 rpm lifting the front wheel skyward. To keep cost low, the H1 initially came with drum brakes front and rear, but comparison tests showed the braking distances second only to the Honda 750 in repeated use due to the bikes low weight.

While the two-stroke power of the H1 could keep pace or exceed other bikes of the time, it was loud, smoky, and difficult to keep in tune. It did achieve some success with amateur racers who would rebuild damaged street bikes for a low price and turn the H1 into a drag race or road racing machine.

Specifications:

Engine displacement: 498cc
Horsepower: 60 hp
Top Speed: 124 mph
1/4 Mile time: 12.4 sec

+ 1971 BSA A75 Rocket 3

This BSA Rocket 3 is a rare ‘export’ version from 1971. It is among the last motorcycles produced by the BSA factory. Fully restored, it has covered only 2,000 miles since new.

The BSA A75 Rocket 3 was developed alongside the Triumph Trident and launched in 1969, just weeks before the all-conquering Honda CB750 was revealed at the Tokyo Motorcycle Show. BSA’s press-release described the Rocket 3 as “having unprecedented beauty… and sleek styling”. Priced at $1,750 it was significantly more expensive than the $1,295 Honda CB750.

Cycle magazine included the Rocket 3 in their first Superbike shootout in 1970. Early production bikes were heavy and drag-strip performance was badly affected, with the BSA taking last place. Higher praise was given for strong high-speed behavior, but most testers agreed the Rocket 3 was over-shadowed by the 4-cylinder, disc-braked Honda CB750.

BSA emphasized the performance of their new machine, taking four completely-stock Rocket 3s to Daytona for a two-day record-breaking attempt. Under Florida’s baking sunshine, the four BSAs performed flawlessly, claiming AMA records for one hour (at 127mph), 200 miles (average 123mph), and an amazing 132mph over 5 miles. At launch, the Rocket 3 featured bulky, square bodywork design, the work of design consultants Ogle Design. Received poorly, BSA explored various options tailed for American tastes, leading to a dramatic 1971 design by Craig Vetter. Management indecision delayed production, but eventually the new design appeared as the X-75 Hurricane, a Triumph model as BSA was by then out of business.

BSA (the Birmingham Small Arms Company) started in 1861 and originally producing bicycles and guns. After building their first motorcycle in 1910 they expanded rapidly, justifying their slogan “The World’s Most Popular Motorcycle” by the 1920s.

Specifications:

740cc three-cylinder
air-cooled OHV motor
58bhp
5-speed transmission
40mpg
122mph top speed

+ 1972 Kawasaki 750 H2 Mach IV

The fastest motorcycle you could buy in 1972 was the Kawasaki 750 H2 Mach IV, a three-cylinder two cycle powering a lightweight tubular frame. The motorcycle on display was designed for experienced riders and has been further modified from stock with aftermarket expansion chamber exhausts, free flow air cleaners in place of the stock airbox, upgraded rear shock absorbers, and wider wheels and tires, all in the interest of improving performance. In 1971, Kawasaki built on the success of their H1 500cc street triple by introducing a larger displacement version with an improved ignition system that could out-run all other large displacement street machines from other manufacturers. Kawasaki was aware that the H1 suffered in the handling department when designing the H2 750, but still came up a bit short in modifications as the 74- horsepower engine put considerable strain on frame and suspension components when cornering or braking. With a staggering power to weight ratio, but limited handling capabilities, the H2 was dubbed “The Widowmaker” due to the high rate of accidents caused by sub-par handling. Kawasaki went so far as to install an adjustable steering damper to minimize wobbles and shaking due to frame flex under acceleration and cornering. Since various components were deemed inadequate by owners for high speeds, the drilled ventilated dual disc brake system which appears on this bike was added to improve brake performance and replaces a stock single disc front brake.
Kawasaki engineers had been challenged by the introduction of the Honda CB750k 4 cylinder “superbike” in 1969 and while they had an even higher performance 4 stroke 4-cylinder bike in development alongside their H1 500cc triple, the early 70’s had become an arms race to see who could build the fastest street bike for the public. Supremacy in this category was judged by quarter mile acceleration and the differences came down to tenths of a second. Aftermarket companies were quick to offer modified intake and exhaust systems from custom tuners like Bill Weigel further increased speed at the track and drag strip. The H2 featured a sleek rear cowling that covered the tail-light for a more aerodynamic shape and a long narrow seat allowing riders to slide back for better wind resistance. In an effort to keep weight to a minimum, there was no electric start on the H2 although kickstarting the 3 cylinder engine was reasonably accomplished. The H2 Mach IV was last built in 1975 having been replaced by the Z1 and KZ900 model 4 cylinder 4 stroke bikes.

Specifications

Engine displacement : 748cc
Horsepower: 74hp
Top Speed: 126 mph
Quarter Mile Time: 12.0 seconds
Weight: 422 lbs

+ 1974 Ducati 750 Sport

This 1974 Ducati 750 Sport is from the Razee Collection in North Kingstown, Rhode Island. It is unrestored even featuring its original tires! At the start of the early 1970s Ducati needed a change as they had reached the end of technical possibilities of a single cylinder engine, especially with the rise of the Honda CB750. Thus, Ducati launched the 750 GT which was engineered by Fabio Taglioni and combined two single cylinder bevel drive engines and created a 90 ° L-Twin. This was the first Ducati to feature the characteristic L-Twin motor in 1971. In 1972, racer Paul Smart rode a Ducati 750 Imola to victory at the Imola 200 which cemented Ducati’s name as a winner. In that same year, the 750 Sport was launched. It utilized the 750 GT frame. In 1974, the Sport’s fiberglass fuel tank was replaced with a steel one along with a narrower rear sub frame and outboard rear shocks. The Sport featured sporty clip-on bars and rear set foot pegs and Dell’Orto PHF32A carburettors. The 750 Sport could be ordered with a half fairing and twin disk brakes if necessary.

The 750 Sport was the fastest and most powerful Ducati made up until that point. This in turn was a steppingstone for creating larger capacity motorcycles to take on higher speeds and the rest is history.

Specifications:

Four Stroke Air Cooled 90 degree V-Twin
62HP
5-Speed Gearbox
131mph Top Speed

+ 1974 Norton Commando 850

Norton’s new Commando debuted at London’s Earl’s Court Motorcycle show in 1967 as a twin-cylinder 745cc machine with a ‘hemi’ cylinder head. Eagerly received, it went on to win the UK’s “Machine of the Year” award for a record 5 consecutive years, a remarkable success. The Commando featured a revolutionary ‘isolastic’ system, which isolated the entire drivetrain from the frame, giving the Commando an unusually smooth, vibration-free ride. In 1973 the engine capacity was increased to 828cc, a front disc brake was added, and the bike renamed the Commando 850.

Cycle magazine included a Commando 750S in their 1970 Superbike shootout, praising the motor’s strong torque, rapid acceleration and confident handling. As a result, Norton decided to invest in growing their US market and booked the magazine’s inside front cover page for a long-running series of advertisements.

Cycle’s 1973 Superbike Seven test included the Commando 850 Roadster, which finished 4th overall. Even against the latest models from Kawasaki and Ducati, Cycle concluded the Norton “did extraordinarily well”, beating both the Ducati 750GT and the Honda CB750.

During its 10-year production run, the Commando was offered in a wide range of variants. The original model, called the ‘Fastback’ was joined by the scrambler-style ‘S’ type, which had a high-level exhaust system and smaller 2.5-gallon gas tank. Later models included the semi-custom ‘Hi-Rider’, the ‘Fastback Long-Range’ with additional fuel capacity, and the ‘Interpol’ police model. A high-performance ‘Combat’ model appeared briefly in 1972 but was quickly withdrawn due to catastrophic main bearing failures. When the 850 models appeared, an ‘Interstate’ model with a 6-gallon fuel tank replaced the ‘Fastback Long-Range’ model.

In 1975, the Commando 850 Mark 3 appeared, which featured front and rear disc brakes, an electric starter and a left-side shifter, now mandatory for all motorcycles sold in the USA. The Mark 3 only lasted until 1977, but the Commando is now widely appreciated and considered to be the last of the classic British twin-cylinder machines.  

Specifications:

828cc two-cylinder, air-cooled OHV motor, 60bhp,
4-speed transmission
45mpg; 115mph top speed

+ 1974 Triumph Trident T150V

The Triumph Trident was developed in response to Honda’s 4-cylinder CB750, which took the motorcycle world by storm at its 1969 launch. Essentially a 500cc twin with a third cylinder, the Trident was very fast and smooth, with superb handling and was received enthusiastically.

Many engine components were shared with BSA’s Rocket 3, but the two companies insisted on their own individual styling. In September 1968, when both the Trident and the Rocket 3 were officially revealed, Cycle magazine said in their first test of the Trident “there isn’t another machine like it in the world”. They were correct for just 4 weeks, when the Honda CB750 appeared at the Tokyo Motorcycle Show, instantly eclipsing the Trident.

The Trident was included in Cycle magazine’s 1973 Superbike Seven comparison, finishing third overall. Testers praised the strong acceleration in the quarter mile – barely 0.5 seconds slower than the winning Kawasaki 750 H2 – and the precise, confident handling.

Meanwhile, at the racetrack, it was a different story. From their release in 1968 to the end of their racing career in 1974, the Trident was a force to be reckoned with. Some of the decades top riders found success aboard a Trident – or its BSA Rocket 3 equivalent – including Dick Mann, Gene Romero, Gary Nixon, Mick Grant and Paul Smart. In addition to winning the first US 24-hour endurance race in 1970, the Trident took 6 first places in the 750cc Production TT races at the Isle of Man.

In 1975, the Trident T150V was replaced by the T160, which featured front and rear disc brakes, an electric starter and left-side shifter for the 5-speed transmission. Finally competitive with the best, it was too little and too late; production of this promising Superbike ended in 1976.  

Specifications:

740cc three-cylinder, air-cooled OHV motor, 58bhp, 5-speed transmission
40mpg; 122mph top speed

+ 1975 Kawasaki Z-1

The 1975 Kawasaki Z1 was built from the start to unseat Honda from the top rung of the motorcycle performance ladder. In 1967 the new high performance engine began development under the code name “New York Steak” first as a 750cc engine but was quickly bumped up in displacement to 900 cc’s after the launch of the Honda CB750 in 1969. Whereas Honda’s multi cylinder 4 stroke had a single overhead camshaft, the new Z1 had twin cams, allowing for higher engine redline due to a lighter valve train.

Before introduction to the public with the US market in mind, Kawasaki engineers disguised the Z1 with Honda paint and badges and drove the bike on US roads and freeways to see what would break. The answer was very little although the bike was fitted with an automatic drive chain oiler to reduce wear. Sales took off for Kawasaki who now offered 3 motorcycles that could achieve sub 13 second quarter mile acceleration times. The Z1 was a pretty motorcycle with flowing painted bodywork from fuel tank to tail light giving the look of speed even when standing still. It was determined that the fastest bike available at the time would be given disk brakes in the front, with an option for twin disks in later models. Handling was considered adequate for the time but the frame was reinforced and improved in 1975 with the introduction of the Z1-B.

At 510 lbs the bike was not a lightweight and the combination of high horsepower with a substantial curb weight meant that tires and brakes did not last long on a Z1. Still, the Z1 was easily the king of the road and many racing teams fitted the Z1 engine to custom frames for endurance road racing and drag racing throughout the decade. The basic DOHC engine and frame design was to grow to 1000cc’s culminating in the race inspired Z1R and KZ1000LTD in 1979.

Specifications:

Engine displacement : 903cc
Horsepower: 82hp
Top Speed: 132 mph
Quarter mile time: 12.2 sec

+ 1976 Honda CB750 K6

Considered the first modern Super Bike, Cycle magazine called the CB750 the most sophisticated production bike ever. In an era where the largest, most powerful bikes used 2- cylinder engines with pushrod valve actuation, the CB became the first production bike to feature an inline 4 cylinder transverse overhead cam engine with electric start.

With a 5 speed transmission and chain drive, the CB750K could travel long distances in comfort, rivaling Harley Davidson and European twin cylinder big bore bikes from Triumph, Norton, BSA and BMW. The result was a smooth, reliable, quiet, machine that achieved at top speed of 120mph and backed up its performance with a series of wins in US and International competitions. Company founder Soichiro Honda targeted the US market with the 750 after meeting with many dealers and racing team owners who urged him to build a “King of Motorcycles”. Honda responded by developing an engine based on his proven 4-, 5-, and 6-cylinder racing machines and adding features like front disk brakes and a 4 into 4 exhaust system. The selling price new was $1495 in 1969.

Unsure of its reception, Honda lacked the tooling for mass production of the inaugural 1969 model and rather than die casting the engine crank cases from aluminum, they were cast in a permanent mold casting adding to the hand built quality of the machine. There were few changes in the CB750 up until 1975 when a second model was introduced called the CB750F Supersport. Styling was modernized with a plastic cowl tail section added to the rear of the seat, disk brakes front and rear, and a race inspired 4 into 1 exhaust system bolted to a black painted engine. The same year Honda also offered the CB750A with a two speed transmission with a torque converter that allows clutch less shifting between the gears.

This 1976 K model on display remains in essentially original condition with over 29k miles save new chain, tires, and seat cover. It’s Antares Red paint was the only color offered for 1976 in the K model 750.

Specifications: