1971 Honda CL450


Below two well-written articles about the CL450 have been reproduced for your reading pleasure.

Forty years ago, a Honda 450 was easy to find.  Thousands were built for people who wanted to get to school or work.  They were well made and sold for a reasonable price to people who, as often as not, didn’t keep up the maintenance schedule.  Most were used, abused and put away wet.  Today, what was once a common bike is becoming a rarity.

In the beginning…...

Honda started exporting motorcycles to the United States in 1959.  After a rocky start, sales took off, especially after the “You Meet the Nicest People on a Honda” advertising campaign.  Yoshiro Harada, in charge of the development of the 450, is quoted in Honda’s official history as saying, “In 1960, 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 British manufacturers were coasting on their success, distributing as much of their profits to shareholders as possible and not upgrading their factories.  In contrast, Honda had put its profits into a state-of-the-art manufacturing plant in Suzuka, Japan.  Up and running in 1960, the new factory could turn out highly developed motorcycles at reasonable cost.  Quality control — apparently of little interest to the British companies — was a byword in Japan.  For some reason, the British believed that their Japanese counterparts had no interest in building large capacity motorcycles.  They were wrong.

In 1964, the British industry received a shock when a visiting journalist discovered a mid-sized twin undergoing tests on the Suzuka track.  Honda’s CB450, aka the Black Bomber, appeared in the U.S. in August 1965.  Power came from a 444 cc dual overhead cam parallel twin, making it the first mass-produced dual overhead cam motorcycle. Running 8.5:1 compression with a 180-degree crankshaft, Honda claimed 43 horsepower at the crankshaft and a top speed of 98 mph.

Unhappy British factory managers took some comfort in the not-so-great handling, the somewhat strange gear ratios, the less than optimal styling and the less than adequate rear shocks.  Although comparatively expensive at about $1,000 (a 1966 Triumph T120R was $1,309), the new CB450 sold anyway, although not in the huge numbers that Honda had anticipated.  Even so, it was fast, had good brakes, started on a button and did not leak oil.  To riders looking to get to school or work and have a little fun on weekends, the lack of handling was trumped by excellent reliability.

Going offroad…..

Offroading was very popular in Sixties America, and bikes that at least looked like they could do some cow trailing sold well.  In 1967, Honda offered a kit with high pipes and braced handlebars to transform the Black Bomber into a cow trailer.  The kits sold, and the first factory-produced CLs, with a more stylish tank and the high pipes and off-road handlebars, were in showrooms in February 1968.

Where the Bomber came only in basic black, the CL offered a choice of candy red, candy blue, or silver.  A reworked transmission boasted five (better spaced) speeds and compression increased to 9:1.  In line with its cow-trailing abilities, torque increased to 29 ft/lb at 7,000 rpm while output increased slightly to 45 horsepower at 9,000 rpm.  Separate tachometer and speedometer units replaced the Bomber’s strange-looking single instrument cluster, and the CL was 12 pounds lighter than the Bomber and had more ground clearance.

Cycle World published a review of the CL and its road-going sister, the CB450K1, in its May 1968 issue and was impressed:  “These are motorcycles that exude visual appeal, a revitalized large bore image, and exhibit what well-considered engineering can do to evolve a distinctly improved product.”  The testers liked the 32 mm Keihin constant velocity carburetors for their smooth power delivery, the improved electric starter, and the 8-inch twin-leading-shoe front brake.  Niggles were few.  One of the CL’s exhaust heat shields vibrated loose during testing, and the speedometer was more than a little optimistic:  An indicated 70 mph was actually 62.41 mph.

When the Honda CB750 came out in 1969, the 450 became Honda’s junior big bike.  The styling was revised to mimic the CB750, but otherwise model development mostly ceased.  The CB450 got a front disc brake in 1970, but since Honda was unsure about discs offroad the CL stuck with its effective twin-leading-shoe drum.

By 1974, its last year, the 450 was showing its age, but still doing well what it had been built to do in the Sixties:  Get people to their destination, with a little fun and a minimum of fuss.

As Cycle said in its April 1974 test of the CB450K7, “For the people who want to tour at posted speed limits and don’t intend to get brave and frisky on winding roads, the 450 is fine.  Not the best, but fine.…a reliable motorcycle that delivers excellent transportation and has the added capability of leisurely touring.  A lot of bikes should be lucky enough to have a niche that broad.”


Honda bumped the CB450’s engine to 500 cc in 1975 for the CB500T, but finally discontinued the model in 1977.  That was 40 years ago, and as time went by, the large numbers of CLs on the road began to diminish; even the strongest, most reliable motorcycle can only put up with so much abuse and neglect.


By 1965, Honda was the world's largest motorcycle manufacturer.  It dominated grand prix road racing and the US market but the largest Honda was still the 305 cc CB77 Super Hawk.  The large capacity motorcycle market was still the preserve of the British but that was about to change.  Spy pictures taken in October 1964, showed a new Honda large-capacity twin in the final development stages and, in March 1965, Honda announced the double-overhead camshaft CB450.

As with the CB77, Honda chose an unusual capacity and, in an era where all large-capacity motorcycles featured engines with pushrod-operated overhead valves, the CB450 was exceptionally advanced.

At the time, many skeptics didn't even believe it was a bona fide production model.  But the CB450 was no hoax and signified Honda's intention to dominate motorcycle production in all displacement classes.

As with all Japanese motorcycles of this period, and even into the 1980s, the engine dominated the CB450.  This all-alloy unit, with horizontally split crankcases, was the first mass-produced double-overhead camshaft motorcycle engine.  The crankshaft was supported by four roller bearings and export versions featured a 180° crankshaft, with two sets of ignition points.  Primary drive was by straight-cut gears to a wet multi-plate clutch and four-speed gearbox with very odd ratios.  The bore and stroke was 70 mm x 57.8 mm, providing a displacement of 444 cc, and the compression ratio a mild 8.5:1.

A double-overhead-camshaft cylinder set the CB450 apart with the twin camshafts driven by an extremely long chain.  Valve sizes were 35 mm and 31 mm with the valves set at a quite unfashionable angle of 80° in the cylinder head with a cast-iron skull as on the CB77.  The most unusual aspect of the design was the use of torsion bars instead of coil valve springs.  These torsion bars twisted under a load acting perpendicular to the rod's axis, and speculation that their service life would be short proved unfounded.  Valve clearances were accomplished by a clever system of eccentric shafts.  Another innovation initially greeted with scepticism was the use of automotive-style, 36 mm Keihin constant vacuum carburetors.  With 31.6 kW (43hp), the first 'Black Bomber' could run to 170 km/h (106 mph) - more than equal to most British 500s.

Although the CB450 was greeted with awe and received incredible publicity for its amazing technology, it wasn't warmly received.  The finish was exemplary, it didn't leak or use oil, the 12V electrics were reliable as was the convenient electric start, but the functional CB450 lacked style and grace.  The handling was limp, the Japanese Dunlop tyres incredibly slippery, the seat seemed made of cast iron, and it was considered ugly.  Early bikes suffered oil pump and carburetion problems but, generally, the CB450 was extremely reliable.  In the first year, sales fell far short of expectations but it wasn't until 1968 that an updated model appeared, joined by a scrambler version, the CL450.

Honda had produced scramblers alongside the CB72 Dream and CB77 Hawk from 1962. These were Honda's first attempts at a dual-purpose design and they ended up more popular than the Hawks and Dreams in America.  With the disappointing reception of the CB450, the introduction of the CL450 scrambler was inevitable.  The engine now incorporated a five-speed transmission and included a new crankshaft, oil pump and clutch.

The compression ratio went up to 9:1 and, while the CB450's carbs were downsized to 32 mm, the CL retained the 36 mm carbs.  Power for the CL was 31.6 kW (43 hp) at 8000 rpm, slightly less than the new CB450's 33.1kW (45hp).

Setting the CL450 Scrambler apart was a high exhaust system on the left and a 19 in front wheel.  Unlike the CB450 that eventually adopted a front disc brake, the CL always had a 200 mm double-leading-shoe drum brake.

However, the CL was no lightweight at 188 kg and it wasn't really the dual-purpose motorcycle it looked.  You also couldn't ride very far on its 9 liter fuel tank.

Later versions were slightly detuned (down to 30.2 kW/41 hp) but essentially unchanged and, by 1974, the 450 was finished.

Despite its technical innovation, Honda completely missed the mark with the CB/CL450.  It may have been enough to scare the British motorcycle industry in 1965 but it was always slow and overweight.  Later developments did little to increase the 450s appeal and, ultimately, the success of a new generation which included Honda's own CB500 Four ensured the 450's demise.

450 Fast Facts…..

During 1967, Bob Hansen in Wisconsin prepared four CR450s for AMA racing. The 142 kg (313 lb) racers were capable of around 220 km/h (137 mph) but the machines didn't live up to expectations at Daytona.

The following year Bill Lyons on a privately entered CB450 won the 100-mile Amateur race at Daytona.  His CB450 weighed 161 kg (354 lb) and was capable of 215 km/h (134 mph).

Bill Penny gave Honda its first production race win at the Isle of Man in 1969, winning the 500 cc class at an average speed of 142 km/h (88 mph).  John Williams repeated this in 1971 at 146.5 km/h (91 mph), nearly 5 km/h faster than Bill Smith's victory in the same event two years later on a new CB500 four.

A 1968 CB450K1 had the distinction of being the 10,000,000th Honda to roll off the production line.

The final variant of the CB450 was the uninspiring 498 cc CB500T of 1975 and 1976.  Described by Honda as the "Neo-Classic Twin for Mature Motorcyclists", the overweight (193 kg/425 lb) CB500T was also slower than the 450, with a top speed of only 153 km/h (95 mph).

The 1971 CL450K4 came in three colors:  Candy Topaz Orange, Strato Blue Metallic, and Poppy Yellow Metallic.