From our Old Bike Archives – Issue 88 – first published in 2020.
Story and photos: Jim Scaysbrook
Street Scramblers were all the rage in the swinging ‘sixties, although few saw any kind of off-road action. They looked cool though, and still do…
The first that we colonials saw of the all-new (well, not really all new) Honda CL450 Street Scrambler was in 1968; a neat 5-speed DOHC twin totally removed (visually at least) from the cobby CB450 ‘Black Bomber’ that had been around since 1965.
That original motorcycle polarised opinion like few before it. The specification was mouth watering; a twin cylinder, all-alloy double overhead camshaft (a first for a mass-produced motorcycle) with torsion bar operation of the rockers that replaced conventional valve springs – as used on the French Panhard small sedan cars from 1948-1959. Horizontally-split crankcases offered relief from the traditional oil leakage of vertically-split cases. 12 volt electrics with push-button starting was a big selling point. In performance terms, the CB450 could live with most of the big British twins, and eat quite a few of them, and, amongst the Brits at least, this had two effects; admiration and disdain. Admiration for the astounding performance from a ‘little’ 450 twin, and disdain that Honda should dare trespass into the sacred domain of the British parallel twin.
But it was the styling that most polarised opinion. The CB450 sported an unusual, high-humped wedge-shaped fuel tank with chrome plated side panels affixed to the main tank, which caused much head scratching. The head light shell incorporated a very Japanese speedo and tacho rather than the separate instruments so beloved of the café racer set, the suspension, particularly the rear, was on the squishy side, and ground clearance was minimal. And then there was the very odd selection of gear ratios for the 4-speed transmission (similar to that which afflicted the CB72/77) that used a very low first gear with a yawning gap to second. This not only flattened initial acceleration and required the rider to get the maximum velocity out of first gear before snatching second, but had the reverse effect when changing back; second was too high for heavy city traffic, and first way too low, and hitting first at a reasonable click, and without a hefty rev on change back, left the rider with the distinct fear of being launched over the handlebars. Carburation too was on the wobbly side; with inconsistent fuel delivery producing rough running. Interestingly, all export models used a crankshaft with 180-degree firing, while Japanese market 450s had a 360-degree crank.
Honda was certainly aware of these shortcomings, and was hard at work on remedies almost as soon as the CB450 was launched to worldwide markets, but these things take time. There was also the small issue of the fairly considerable number of 4-speed 450s that had been flogged to dealers, so the timing for a replacement model was an issue of considerable delicacy.
Problem-solution. A quick fix.
For the vital US market, Honda tackled the styling and mechanical solutions separately. What they came up with (with forceful input from US Honda) was an interim model that was officially marketed as the CB450 Super Sports. Very little is known of these and it is believed less than 50 survive world-wide. The Super Sports was sold as a complete bike, while dealers were also able to access what became known (officially or unofficially) as the D Kit. This kit was designed to convert the standard CB450 ‘Black Bomber (which also came in red, but Red Bomber does not have the same ring to it) to what resembled the CL72/77 ‘Street Scrambler’. The kit comprised a new fuel tank of much more traditional appearance and complete with rubber knee pads, twin high-mounted exhaust pipes with fat mufflers protected by perforated heat shields, small midriff side covers, spring-loaded footrests, lighter and shorter mudguards, higher handlebars and a choice of three colours: silver, red or blue. More than half a century later, official specifications for the model are all-but non-existent, but it would seem there would also need to be a revised air filter arrangement, since the high pipes invade the space occupied by the CB450 system.
While a small number of complete 450 Super Sports were sold through dealers, the ‘D Kits’ were often raided rather than being used complete to convert Black Bombers to the new, or interim model. Fuel tanks in particular were often switched to models languishing on the showroom floor. The Super Sports was certainly an interim model, with a deliberately short shelf life, because at virtually the same time, late in 1967, the second generation CB450, designated K1, was ready to roll out of the factory and onto waiting ships. And with it was the second iteration of the Super Sports, the CL450. With Honda’s decision to abandon its costly Grand Prix team, there were renewed resources, both human and financial, to get the house in order for the bread-and-butter sales.
Both these models shared the same basic structure, but vitally, incorporated a 5-speed transmission, effectively squeezing the extra cog between first and second. The entire box was redesigned for smooth operation, with needle and ball bearings for mainshaft and countershaft. The detent mechanism was improved to make locating neutral easier and for more positive gear selection. The new transmission used a sliding gear on the kick starter which disengaged from the countershaft first gear when not in use. On the original model, an idler gear was in constant engagement. All this added up to far less friction and drag, and hence more power, but were certainly more expensive to manufacture. The extra hardware in the gearbox required wider castings as well. These changes alone made a world of difference to the riding experience, but there was more.
Enter the CL
The CL450 used a fuel tank even smaller than the Super Sports, although it was visually similar apart from the lack of knee pads, and there was now a separate speedo and tacho. These were produced in sturdy black plastic cases, the speedo incorporating an odometer but without a trip-meter. The engine itself was quite heavily revised from the CB450, with a new crankshaft, oil pump and clutch, while valve sizes were up (with higher seat pressures), along with the compression ratio, and the power output of 45 horsepower at 9,000 rpm – up by 2hp. Carbs, although still 32mm CV style Keihin Seikis, were heavily modified (and exhaustively tested) to provide smoother running.
The riding experience was further, if marginally, improved by new suspension. While the front forks were little changed with the exception of neoprene gaiters instead of metal covers, the rear shock absorbers were completely new. The original CB450 was fitted with conventional oil-damped hydraulic units, while the K1 and CL450 used a De Carbon type. These had two concentric cylinders containing a conventional piston with a two-way valve, and a free piston with an O-ring seal. In the upper cylinder, a sealed rubber chamber holding nitrogen gas at high pressure sat at the base of the oil-filled reservoir, while oil flowed through the valves in the conventional way. Expansion of the gas in the chamber forced the rubber bag upwards to follow the path of the free piston. It sounded impressive, but early road testers were still short on praise for the overall handling performance.
Brakes, while ostensibly unchanged from the original model, had been subtly re-configured to give increased efficiency and were reckoned to work beyond reproach. Indeed, later in the piece when the CB750-style disc front brake arrived on the 1970 model, many reckoned it inferior to the original drum. It was however, indisputably cheaper to produce. The CL450 retained a drum front brake for its entire production life, which stretched to 1972.
Apart from the tank and mudguards, the CL450’s visual standout was clearly the high-mounted exhaust system; not the one-pipe-per-side style of the Super Sports, but with both exhaust pipes exiting on the left and joining a single muffler of rather generous proportions, again with a pair of ornately formed heat shields that nevertheless sat uncomfortably close to the pillion passenger’s left leg. A pair of stubby tail pipes completed the package, which announced its existence with a distinctive raspy note. Most tests comparing the new CB450K1 with the CL found that the CB had a slightly higher top speed, and this was generally ascribed to the CL’s exhaust system being more restrictive than the twin mufflers on the CB.
The CL’s handlebars became motocross-style; high, wide and fairly straight, with the usual cross bar.Both the CL and the CB shared the same seat; well padded and comfortable, with a pressed alloy base trim held in place by invisible studs.
Stateside immigrant
Our featured CL450 is a 1968 model that was imported some years from the USA. Owner Clyde Ikin purchased the 450 in several boxes and began an extensive campaign to identify genuine and non-genuine parts, and to hunt out a few missing bits. The speedo and tacho were from a later 1972 model, but the originals were found, although Clyde says he may use the later units. These incorporate a trip-meter and sit on opposite sides to the originals and have metal bodies rather than plastic. One item that took a bit of work was the seat, which was recovered and fitted with foam of the wrong density, and with the alloy trim damaged. A major hunt uncovered a new, genuine cover, the correct foam and a new trim strip, discovered at a swap meet. You can be lucky.
Clyde says the engine rebuild presented few problems. “The bottom end was fine, so that was left alone. The bores only needed a light hone, had the valve seats re-cut and the valves faced, and I found that the piston rings from the later CB500T fit and are actually better because the oil ring is a three-piece type instead of the original single piece. I put a new cam chain in – this has to be the longest I’ve ever seen. I thought a Kawasaki Z1 chain was long but this is six links longer again – 128 links. The only change I made to the engine was to fit a later oil pump from 1971. These had a 19mm bore instead of 16mm so they deliver about 30% more oil and I reckon that’s a good mod to get oil to the top end quicker. The only other thing wrong was the starter motor clutch had gone, but that’s pretty common so I just sourced a new rotor, a pair of springs and rollers.
“Some of the rubbers are hard to get but when you look a bit closer a lot of this is common with other models. The stems for the rear indicators for instance are the same as on a Honda 750 four, but they are a 450 part number. The mounting rubbers are different though, and these are hard to find.”
The CL450 was short-lived – in production for just five years and unchanged throughout, including the drum front brake – but more than 50 years since its creation, the design still has a lot going for it. Street Scramblers on the whole were a ‘sixties concept that was seen as passé as the new decade swept in, bringing with it a fresh generation of multi-cylinder road burners, and before long, the true dual-purpose motorcycles that are today so universally popular. But few exude the character and panache of the CL450.
Specifications: 1968 Honda CL450
Engine: DOHC parallel twin, 180-degree crankshaft.
Capacity: 444cc
Bore x stroke: 70mm x 57.8mm
Compression ratio: 9.0:1
Oil system: Wet Sump
Carburation: 2 x Keihin Seiki 32mm CV
Air filter: Paper element
Ignition: Battery and coil.
Fuel capacity: 9 litres
Starting: Electric or kick
Transmission: Gear primary drive, 5-speed.
Gear ratios:
5th: 6.50:1
4th: 7.71:1
3rd: 9.70:1
2nd: 12.61:1
1st: 18.59:1
Wheelbase: 1367mm
Seat height: 800mm
Curb weight: 181.3kg
Top speed: 105.7 mph (170.2 km/h)
